Vehicle fruad.

I have bought a Volvo S40 from webuycars joburg South branch 3 weeks ago. The vehicle had an airbag fault indicator on the dashboard. And the sales rap assured me that it was the only issue with the vehicle and that once I take it to the service the issue we'll be resolved. When I took the vehicle to the service I was told that the computer box in the vehicle was incompatible and its a Volvo V50 computer box instead of Volvo S40 therefore they won't be able to diagnose the vehicle, they advised me to take the vehicle back to the dealership. I spoke to the sales rap and he told me to get a quote from Volvo and I did excetly that, the quote from Volvo was R100 000.00 and webuycars rejected the quote and advised me to get a quote for at least R30 000. When I couldn't find it they said I have signed an acceptance contract for liability of defects on the vehicle. All I want is my money back or a vehicle replacement.