Telling her from the off to contact warranty company was a mistake.Although she had only had the car for a short time,you appear to have given the impression that she was on her own,it was not your problem.Next time this happens,tell the customer to get the garage to put it back together,then get it collected and either fix it or give a full refund.The fact you reduced the price does not matter.If she takes advice and it goes to a small claims court she can claim far more than the sales price and win.The bottom line is,we are not popular people,when there is a problem,we are always viewed as being in the wrong.In my experience,It is always cheaper to "nip things in the bud".If you have a pitch,these things things happen several times per year !