The new owner told me that he even didn't want to buy that player and will put him back on the market, at twice the price he bought him :-(
I'm really fed up of all these bugs. I subscribed to the supporter pack a week ago because I liked the game and, a couple of hours later, the problems started. Now, everytime I try to buy a player, something wrong occurs in the auction and I find myself without the player... If it had happened a few hours earlier, I would definitely not have subscribed to the supporter pack...