sold my car now his want money back , help

i sold my car on ebay , despcrit all the problem on the car ,

my adv"Car will be sold as seen, this is a used car so might have some wear which I might have missed."


after 2 hours the buyer call me , said got problem on the car , "overheating "

and ask me about 400 pound back to fixed head gasket , i don't know it's ture or not , because when i drived car was fine .

on my adv has mentioned :
"water leaking happened last month , when drive on the motor way cause high temperature , has been fixed , after this drive about 200 miles , no problem "

but the problem has been fixed , so i think maybe the problem come back ? i agreed with him told him give him 400 back .


today i told this to my friend , my friend said maybe this guy just want cheat me some money , i shoudn't give any money back .

so i come here to ask , should i take a reponsiblity about this problem ,even it 's real , should i give money back ? i don't think he is a good buyer because when he come collect the car he picked things on the car which i already montioned on advt , and give him 70 pound discount on bid price already

should i take a reponsiblity about this problem ,even it 's real , should i give money back ?

sorry for my english , thanks for your help


peter