The ultimate aim is for the vast majority of visa applicants to apply, pay for and receive visas through the privatised system, following rules set by the government, with Australian officials only getting involved in difficult cases or to refuse or cancel visa rights.

A Senate hearing in early November heard from former deputy secretary of the immigration department Abul Rizvi, who warned that a UK-style system would mean "ultimately a loss of control in the visa system", where cashed-up migrants would get preferential treatment.

"Don't do it," said an Australian academic in the UK who has recently gone through the UKVCAS (UK Visa and Citizenship Application Services) process, who asked not to be named.

"It's less convenient and more expensive than it was before – and what it was before was not terribly convenient or cheap.

"If you want a system that actually welcomes people then you’re better off running it yourselves."

French firm Sopra Steria was given the contract for UKVCAS, replacing the old paper-based system with a digital online one.

It set up six "core centres" offering a free interview service, plus 51 "enhanced service centres" which charge fees starting at £60 ($115), on top of the standard visa fees.

The "premium lounge service" in London features "spacious seating areas" and high-speed WiFi and charges £200 ($380) for appointments, more on weekends. Some applicants have been forced to choose this option in order to submit their applications on time due to a lack of available free appointments.

Calls to the UKVCAS help line cost £2.50 a minute, and the centres charge extra for interpreters and document translation, and for SMS alerts.

In June MPs and lawyers demanded an independent investigation into the millions of pounds being paid by vulnerable people who were running out of time to renew a visa.

Some universities, worried about the September surge of students seeking visas, considered paying Sopra Steria to set up "pop-up" visa offices on university premises, at a cost of £50 ($95) per 15-minute interview.

The Australian academic said he lived a day's round-trip away from the nearest free appointment site and had to pay for a premium service – but still couldn't find an appointment within three weeks.

He said the old system had drawbacks, such as having to mail documents to the department for processing, but it had been cheaper and more convenient as much of the enrolment and biometrics were done at post offices.

"When a private company signs the contract they generate profits either by charging more for the same service, or by incentivising people to take extra options," he said.

Kelly Webb-Davies, an Australian who arrived in the UK in 2008 to start a PhD and married her Welsh husband in 2012, hit problems trying to get her citizenship application through the new system.

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"It makes no sense that we are paying fees to a private company for processing when we already pay astronomical fees to the Home Office," she said. She had found it hard to get full information on the service fees, and very hard to find an interview appointment anywhere near her home in Llandudno, and was hit with an extra £35 ($65) fee to upload documents.

"I'm not at all happy with the new system because it disadvantages people who don't live near cities, and people who work full time – [they] have to choose between paying appointment fees, or paying to travel far and miss work," Webb-Davies said.

"If we're already paying multiple thousands of pounds (my last visa was £2297 ($4340), and this citizenship application is £1330 ($2510) for the applications, why do we now also have to pay fees to a private company?"

A worker from a public library, which had recently started processing visa and citizenship applications, said Sopra Steria had "massively overbooked" the service and "there were many instances of applicants hysterical and in tears".

"The library was advised not to help applicants, to not check scans thoroughly and so on in order to ensure more appointments could take place."

A spokesman from the UK Home Office said it worked "closely with all partners to make sure they provide an excellent service."

In July Sopra Steria reported revenue growth of 9.6 per cent and net profit up 58.8 per cent from the previous year. Sopra Steria declined to comment for this story.

A spokesman for Home Affairs said the Australian government would always retain "responsibility and accountability" for visa decision making and security checks.