How long did you give the bank to accept the offer? If that time has passed and they haven't responded then tell them you want your escrow back.
But where is the real estate agent in this?
Okay so you put gown a very large amount for what reasons? Are you paying cash for the house? Are you thinking that a large amount in deposit will get you the house? The fastest deals seem to be cash buyers and those a Real Estate Agent wrote the contract that a bigger depoit would be palced if contract excepted. Please make sure you are allowed to have all the inspections a bank would want you to do for peace of mind. A thorough building inspector will tell you if anyhting is wrong and approximately how much it may cost to fix it. Do not jump to fast at someof these deals. You may be in for a shock after you get in it.