Tamworth dealer 89

i have the same at the moment , been doing this job 30 years now , bought a corsa 2011 plate from my dealer and found out after i replaced the bumper and did some paintwork mot etc that the car was a cat "c" , rang my deale rwho said bring it back , ive repaired it now , ok go with it and i will knock some off others..fine ... auto trader said for miles etc it was 3645 , but as i dont deal in cat cars i put it up for 1899 .. guy buys it for his son 1st car, sold them a 12 months warranty with the car ..27 days later get text rejecting the car under the r c act 2015. rang the guy ask why , was told they had to replace the water pump , therm and sensor @ £260 ...and now its broken down.... my reply was why didnt u use the warranty and whats wrong with the car. (offer at my cost to get a local garage to recover it and find out) NO want all my money back AND YOU have to fetch the car ... 90 miles away ... or i will get in touch with trading stand.s and then if not resolved court ... to sumerise bought a cat c car at half price doesnt use the warranty , has cover in ecxess of 600 miles now wants me to get it back and refund total..and it doesnt even run !!!!!.... any advise would be most appreciated .