I used some Mothers QD to remove some tree sap yesterday...it did a good job. The sap was on the car for less than 24 hours. I was not happy the sap was on the car considering the day prior I had just put on a layer of Poorboys EX-P. But on the brightside I think it was better that the PB...
$50 per car is REALLY LOW BUT, you did offer to do that job for that price and you and he agreed to the price...can't say I blame the guy for getting upset. You may have to eat this one...unless you really do not want the business and your reputation will not be adversely impacted.