Victoria's rail union has amplified its call for Melbourne's train and tram systems to be taken away from Metro and Yarra Trams and returned to public ownership, following the release of a report that identifies major deficiencies in how the government handles the contracts.

The union launched a campaign on Thursday, "Public Transport, Public Hands", calling on the Andrews government to walk away from any plan to extend the two franchise agreements for another seven years when they expire in November 2017.  

The operators have been paid a combined $7.6 billion for operating the public transport system since 2009 – $5.4 billion to Metro Trains and $2.2 billion to Yarra Trams – and are expected to meet contractual performance targets set by government. However, Auditor-General Andrew Greaves found the state did not know if the operators were meeting all of the targets.

The Auditor-General's report, released on Wednesday, said: "Weaknesses in the design of the performance regimes and in PTV's contract management mean that it is not extracting maximum value for money from its franchise agreements."

The biggest problems related to a lack of knowledge about maintenance and renewal of the networks, for which the operators have been paid almost $2 billion.  

Luba Grigorovitch​, Victorian branch secretary of the Rail, Tram and Bus Union, said poor maintenance was at the heart of delays and disruptions to passengers.

"If Metro were forced to be transparent, we would see that our trains are late due to deep rotting maintenance issues across trains, tracks and decaying signal systems," Ms Grigorovitch said.

"Metro and Yarra Trams have sucked $7 billion out of the Victorian economy since they took the reins seven years ago, and Victorians have little to show for that shonky investment."

The operators have been paid a combined $7.6 billion for operating the public transport system since 2009. Photo: Craig AbrahamThe Auditor-General's report did identify an improvement in the punctuality and reliability of trains and trams – two of the main performance benchmarks – since Metro and Yarra Trams took over.

A motion to return the train and tram systems to public hands was endorsed by Labor members at the ALP state conference last month, but the Andrews government has given no indication it is considering going down that path.

The government has entered into exclusive negotiations with Yarra Trams over extending its franchise agreement for seven years. Photo: Eddie JimIn a show of faith in the two operators, it has recently entered into exclusive negotiations with Metro and Yarra Trams over extending the franchise agreement for another seven years. But it has flagged tougher conditions in the new contracts, including bans on station skipping and tram "short-shunting", where passengers are forced to disembark prematurely so the tram can be rerouted.

Public Transport Users Association spokesman Daniel Bowen said most passengers did not care if the system was privately or publicly run, only that it worked well.

"We wouldn't want to see the franchises returned to the incumbents without the government carefully considering if it should go to someone else; it shouldn't be an automatic decision," he said.