Dealer does not want to issue a receipt

I again: I bought the L1800 from a Subaru dealer and paid in cash when taking over in the presence of my girlfriend. During various remedial appointments I asked him for a receipt of the purchase amount, but he refused, and stated that he had only “run through” the car, so had sold in the customer’s order, and he would also have received the money from him. I think that’s not true, and he only wants to protect himself from any claims on my part. D Still, what can I do? I have a right to a receipt, right? Does he have to repair the car until it is actually technically perfect (I don’t even talk about rust here)? For example, the holder of the left main headlight is torn, on the cooler the slats detach. Do I claim to have a receipt of the cash payment from him? Does he have to repair until the biggest things have been removed? I thank you for every hint! Thomas