Sales contract via WhatsApp – now withdrawal

Hello, had received a very good offer from an unknown person (only the mobile phone number is known and through WhatsApp, apparently a picture of the person) via WhatsApp… He offered me on 11.05.15 sum X (do not talk about prices 😉 ) via WhatsApp and arrived today, he would offer me proud 25% less, since comparable golf’s would be offered well under his first bid with up to 1 year TÜV and less kilometers. My Golf 3 GTI EZ 93 would have TÜV – so nevertheless sc now he wanted to transfer a down payment already on 11.05.15, because he wanted to pick up the car in the next 2 weeks – the down payment of course did not go to the account until today… In my opinion, I should be entitled to a claim for damages now, because I have to “re-mediate” the car again? He absolutely wanted the car and offered me sum X and wanted to know as when he can get the car and he would transfer down payment and rest then bar against Kaufv bear it… Do you really only know this from the southern countries, who want to act afterwards, but not from a German?!? Nothing against people of other origin, but this is my subjective experience…