First of all, welcome to Buzzerbeater! Even if you don't see that it is abuse, it is abuse! How would you react, if you are not able to sell players for about one Season, because someone "don't like you" and act like kozlodoev said. You probably would ask, why it is possible to withdraw bids. But just go on to the next point...
You don't know why it could bancrupt a manager, if someone else withdraws his bid. You probably dont know, that you are able to spent the money from bids on your players as soon as the bid is made, even if the player is still in your roster. When you now start to bid on another player, with the money that you virtualy already have and someone the bid on your player is deleted, you have to withdraw your own bid. So it looks like we wont see any transfers in the future. Or even worse... if you are not able to login after the withdraw, but you still buy the other player... then you are in debt... and no worst case ;) ... now your "friend" from above dont let you make a transfer...
I dont think, that all of these things would happen... it is just to show you what could happen if you are able to withdraw your bids.
The other aspect you mentioned is, that you weren't told the value of the players. Here I will just ask you two questions:
1) Did you ask for help in the forum, like you did it with this topic here?
2) When you want to buy an new notebook, do you just go into the next shop and buy the first one? Or do you compare several notebooks and different shops?
I know that BB is not real life... but thats not the point for me. Even here in Buzzerbeater you have to live with the consequences for your doings.
Yogi