the AA fella said about 700 pound but have had quotes for 504 , 350 , and berrystreet garage in bootle said 240 all in which seems to good to be true
The Vivaro has a dual mass flywheel. that can cost between £395 & £525. That doesn't include the clutch plate, release bearing, slave cylinder or fitting.
I bet the cheapo was labour and clutch plate. They will come back to you with another quote once they have removed the gearbox and there is nothing you can do then as they will have you by the short and curlys.
Trust the AA. They know.
Phone a local parts supplier and ask for a price on a replacement clutch kit (including DMF.)
Ford and Peugeot/Citroen also have Dual Mass Flywheels, but you can get an upgrade kit that changes them back to a solid flywheel with conventional clutch plate. Something may also be available for Renaults.
DMFs were a disaster. I understand that some new vehicles are no longer supplied with them due to their failure rates.