Two Australian companies that sold internet advertisements and website space have gone bust, leaving thousands of customers out of pocket and without a website for their businesses.

The companies, Yodel Australia and Blink Digital, have debts of $4.5 million and are behind a complex network of businesses.

Customers are demanding answers.

Liquidators are looking into how the companies plunged so deeply into debt and whether any matters need to be referred to the Australian Securities and Investments Commission for further investigation.

Sydney-based Yodel Australia was officially opened as Fulfilnet Australia in 2003 by then prime minister John Howard.

The company began by selling web space but progressed to selling online ads, when it changed its name to Yodel Australia.

Queensland photographer Olya Hilton signed up with Yodel so she could access the popular Google Ads service, but said she had no increase in hits to her site.

"I never, never saw the ad on Google ... and I did not see any increase in traffic at all," she said.

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"What they do is they take money from people, they tell them that they are going to help them increase the traffic, they're going to help them improve their sales and nothing happens."

After signing up with Yodel Australia, Ms Hilton got an unsolicited call from a company called Blink Digital - a wholly-owned subsidiary of Yodel Australia.

Blink Digital representatives offered to increase Ms Hilton's ranking on search engines like Google, but she did not sign up.

Gold Coast life coach and hypnotherapist Reea Pawley signed up with Blink Digital for a service known as search engine optimisation.

Known as "SEO-ing", the service builds key words into the text of a website to boost its ranking on Google searches.

"I paid for three months of SEO-ing and that was supposed to go from October to January," Ms Pawley said.

"By January I had nothing, I had absolutely no presence and I was on page 5,000 on Google still."

After three months, Ms Pawley tried to cancel but said her credit card was charged anyway.

"I'd done everything I could to let them know I wasn't happy with the service. I'd emailed them, I'd done all sorts of things," she said.

"They charged my credit card without my permission, which I was really angry about."

Reea Pawley and Olya Hilton are out of pocket about $1,000 each.

Companies owe millions

The companies owe $4.5 million to creditors, including $160,000 to National Australia Bank and $100,000 to Google.

Google terminated its "preferred partnership" relationship with the company more than two years ago over a payment dispute.

In New South Wales alone, the Office of Fair Trading has received more than 140 complaints about Yodel Australia, Fulfilnet and Blink Digital.

Fair Trading Commissioner Rod Stowe said an investigator visited the business in June to "talk to them about some of the concerns we had with the way in which the business was being conducted".

Despite getting assurances from Yodel Australia that things would be improved, five months later the business was put into liquidation.

Paul Harvell was the managing director of Yodel Australia and Blink Digital, and believes the company grew too big too fast.

"The systems that we had ourselves were not adequate and I'll cop that," he said.

Mr Harvell says some of the problems arose because of companies set up by ex-staffers in competition.

"We had a lot of customers getting very angry with us about billing issues and those issues then transpired to - guess what we lost them to - who would you guess? The guys that have left just last week," he said.

Mr Harvell has left Yodel, but is still in the sales game, working with a former colleague running a consultancy for call centres.

Liquidators are investigating any possible offences by people involved with the company.

Do you know more? email investigations@abc.net.au