Seller forgets transfer costs and wants to pay later!

Hello together, I hope you can help me! I bought a new polo about a financing last Friday! It was also great and I was satisfied. Today I got a call in which it was said that the seller forgot to charge the transfer costs. About transfer costs was never talked about. The transfer costs amount to 750€ (which seems a lot to me). He told me he can grant me the permission (160€) and instead 750€ transfer costs n he would charge me for 500€! If I don’t want to, he can also withdraw from the contract and the contract “break it up”! I don’t have the car if that’s still important, it was planned for this week! How would you behave? Is he himself responsible and has to worry for the car coming into your car dealership and taking care of the costs? Can he just withdraw from the contract? I’m happy about your answers and thank you!