Thousands of holidaymakers appear to have lost money after being directed by TripAdvisor and Trivago to an Asia-based agency called HotelQuickly.

Many readers have contacted The Independent after receiving alarming emails that suggest they may have been scammed – having made full payment, the reservation is then cancelled and a refund offered only in the form of a voucher.

Roy Bamber had booked a four-night stay in Prague this month to celebrate two birthdays. But three days before departure, he says: “The hotel received a cancellation through a middle man.

“We had to pay the hotel again and since then HotelQuickly are only offering a voucher rather than our money being refunded.”

Les Davis said: “It looks as if HotelQuickly are either conning, defrauding or going bankrupt.

“Not sure how many people have lost money with this outfit but I contacted them through TripAdvisor and made a booking for two nights in Bryce Canyon, US, for a trip next May.

“The hotel confirmed the booking which I stupidly paid in full by debit card at the time of booking.” Mr Davis and many other readers have received an email which begins: “Greetings from HotelQuickly!”

The message claims that each booking “was canceled by our supplier without our knowledge and omitted to close their room availability on our system”.

In fact the firm itself is accused of cancelling the bookings, or not having made them in the first place.

The HotelQuickly email goes on to say: “In reference to your refund request, unfortunately, at this time and due to an issue with our system, we are unable to process the refund directly to your card.

“However, we have successfully processed a full refund in the form of a voucher for later use. The refund voucher will be available for you to use any new booking and the voucher can be extended at any time.

“This is the only refund method we have available at the moment.”

Another reader, Christopher Cotton reports: “When you try and use the voucher they offer, there are either no hotels or it states the voucher has been used before. It’s a worthless voucher.”

Some customers took to social media to express their fury with the firms that had led them to HotelQuickly.

John Tweedie tweeted: “@TripAdvisor why are you still advertising HotelQuickly on your site when they have clearly scammed a lot of people.

“My wife meant to fly to Fuerteventura at 6 in the morning and we received a cancellation email today, money gone.”

“Was also sent by @TripAdvisor, which I trusted for years, to this scam,” reported Xiaoqing Pi. “Same story of sudden ‘cancellation’, being left stranded and no refund. The hotel said they’ve never got even one msg from HotelQuickly, nor heard of the website.”

Travellers who re-booked with the same hotel as their original reservation were faced with having to pay again – often at a much higher rate.

Simon Leger asked Trivago: “HotelQuickly is scamming your customers, cancelling all bookings prior to the date and offering future vouchers in exchange instead of refunds, can you help contacting them to resolve the issue please?”

It is not clear if British customers who paid by credit card will be covered by Section 75 of the Consumer Credit Act, which holds the card issuer jointly liable with the supplier for the performance of the contract. If payment is made through an intermediary – as HotelQuickly was – the link can be broken.

Because the firm is based outside the European Union, British travellers may find it near-impossible to secure any recompense.

Customers were steered to HotelQuickly through the travel review forum TripAdvisor and the rate-comparison site, Trivago. Both companies earn a commission on “click-through” bookings.

The Independent contacted TripAdvisor and Trivago to get a response, as well as HotelQuickly. TripAdvisor said it has suspended HotelQuickly from its site, and was "very concerned to hear about the difficulties some HotelQuickly customers are experiencing with their bookings".

It advised customers with an upcoming or outstanding booking to contact the hotel they had reserved directly, to check whether the reservation is still valid. TripAdvisor recommended customers whose payment had already been processed to contact their credit card provider to dispute the charge, if they think the booking isn't valid; and for customers who haven't yet been charged to contact their bank or card provider to block any future payment.

Trivago said it "made the decision to deactivate HotelQuickly until such issues are resolved have a Help Center for our users in the meantime".

"We have been informed that HotelQuickly has been providing refunds to users and is offering a 5-15% voucher off their next reservation with them," said Trivago. "That said, we have noticed that the OTA is crediting the customer's HotelQuickly account only, rather than providing a refund via the original payment method. We are awaiting further explanation on this from HotelQuickly."

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Other media, including the Straits Times in Singapore, have also failed to get a response from HotelQuickly.

HotelQuickly’s parent company is Rising Sun Merchant Services, based in Singapore. It also has an operation in Hong Kong and Bangkok. Most of its bookings were made not direct with hotels but through intermediaries.

This is at odds with what the agency tells customers on its website: “As soon as a booking is made in the app or the website, our system automatically emails the hotel’s reservations department.

“Our team also calls the hotel’s front desk to personally confirm the reservation in some cases.”

The booking agency was set up to emulate the successful firm, Hotel Tonight.

The Athens-based online travel agent, Tripsta, located in Athens, has also closed down. It depended for business on price-comparison websites, and offered very low fares in order to secure bookings.