Sending a letter within Australia is now slower and more expensive. Australia Post has increased the cost of stamps for sending regular letters within the country from 70 cents to $1 – a rise of nearly 43%.

The change to the “Basic Postage Rate”, effective on Monday, comes with the introduction of three delivery speeds for sending letters within Australia: express post, priority and regular.

The regular service is now slower by up to two business days. A letter could take as many as six business days to arrive at its destination.

The new priority service is up to two days faster, with an estimated delivery time of between one and four days – but costs an extra 50 cents for a priority label.

Express Post remains the fastest service, with “guaranteed next-business-day delivery*” – to approximately 80% of Australian addresses, as part of its network operating “between all capital cities (except Darwin and in Perth CBD only) and some major centres”.

In an explanatory video posted on YouTube, Australia Post says the changes are designed to give consumers “more choice over the speed at which you send letters”.

Almost-instantaneous delivery of correspondence of any size, to any destination, is not being offered by the postal service.

Concession card holders can continue to buy regular stamps for 60 cents; the priority service will cost them $1.10.

The price of seasonal greeting stamps remains unchanged.

The increases were expected after Australia Post recorded an annual after-tax loss of $222m in late September – its first loss in 30 years – that group CEO Ahmed Fahour said reflected “terminal and structural decline” in the sending of letters.

Australia Post signalled its intention to increase stamp prices at the time, but first had to secure the approval of the Australian Competition and Consumer Commission. The government granted it regulatory approval to introduce different speeds of service.

Fahour has not commented on the change to services on Twitter, although he had posted on the site on Sunday.

Unusually for the forum, there were no cries of outrage expressed on Twitter over the price increases, but they were discussed with some bitterness on Australia Post’s “National Conservation” forum.

User “Jodiandbrett” said all services bar regular were now “expensive” and “unaffordable”.

“My goodness. I really feel helpless here, does giving my opinion actually make a difference or is it just a place Australia Post have put here for people to ‘feel’ like they can voice their opinions? ... Thank you for letting me vent, as I am sure that’s all this will be good for.”

User “Danny” compared the introduction of the priority label to the pink sticker service offered “back in the 1990s”.

In response, user “Rubblesby” said Fahour “should be sacked”. “He took what was once a proud Australian institution that people loved and trusted and turned it into a self serving honey pot”.

No dollar stamps were available for sale in Australia Post’s online store today, and priority stamps were out of stock.