Critics say that Sanral should have questioned the escalating costs of the highway project.
The implementation of e-tolls on Gauteng's highways has been met with mixed reaction, including further promises of court action.
Justice Project South Africa lawyers have labelled responses from Sanral's legal team relating to e-tolls as "arrogant and evasive".
Cosatu seems confident that civil disobedience will prevent the success of e-tolling, despite its offical launch on Tuesday.
With an 11th-hour attempt to stop e-tolling by the FF Plus also dismissed, Gauteng motorists will to have to face paying for the use of highways.
An application by the Freedom Front Plus to stop the implementation of e-tolls has been struck off the roll at the high court in Pretoria.
The electronic tolling system on Gauteng's highways is expected to go live at midnight on Monday.
Sanral has threatened legal action against Justice Project SA following its request for clarification on e-toll prosecutions, says the organisation.
Gauteng has sought to assure motorists it will maintain roads that can serve as an alternative to tolled routes.
E-toll stores in malls across Gauteng have been quiet ahead of the arrival of the controversial e-tolling of the province's highways.
A hefty bill awaits non-registered motorists without e-toll accounts who fail to pay for e-tolling within a week.
After warnings that motorists will be charged if they don't pay e-toll bills, a law firm has offered to defend the first non-compliant e-toll user.
Outa says the e-tolling saga has caused Jacob Zuma to miss out on a chance to show the country what consultation and participation actually means.
Parliament's transport portfolio committee says Cosatu and Outa's call for motorists not to pay for e-tolls in Gauteng defies the Constitution.
Reports say the justice department and Sanral are mooting the possibility of establishing special courts to prosecute those who don't pay e-tolls.
Cabinet says it has faith that the public will abide by the law and buy e-tags, calling on Gauteng's inhabitants to "demonstrate good citizenship".
Outa says it thought President Jacob Zuma would take more time to make a decision about signing the Bill that has given e-tolling the go-ahead.
President Jacob Zuma has signed into law the Transport Laws and Related Matters Amendment Bill, giving the go-ahead to e-tolling in Gauteng.
There's still no definite start date, but Transport Minister Dipuo Peters says e-tolling will be up and running before the year is out.
The South African National Roads Agency has again been downgraded by ratings agency Moody's thanks to prolonged battles over e-tolls.