How can i cancel my auction.com bid after I have won

[Amaju E.]

I won an auction on Auction.com that I didn't expect to win--now I have more questions. Long story short, my initial research said the house was worth way more than I subsequently found it to be worth. The house is occupied but I have no access to the property to get access. 
What happens if I pull out of the contract? I have other auctions going which made me make deposits of $2.5K as holds on my CC. Would they go after those?

Any assistance or advice will be well appreciated.