The gearbox splines have gone on my Renault Scenic. I need to know if I'm being ripped off here.?

The garage wants to charge me �320 labour to get the gearbox in and out, �175 for parts and another �300 labour for the work. All in all about �800 plus Vat....and I don't even get a new gearbox! If the clutch has gone as well this is going to be a grand plus. Help!