Bonny, I used to work for a bank and the best advice I can give you is to....don't give up. They can and do refund money on fraudulent withdrawals and that is exactly what took place. Don't know the size of your bank but if you have a loan officer there, speak with him/her, don't just deal with bookkeeping. Explain that you have been a valued customer with no account problems for the past 20 years and want to remain their customer, but you can not afford to be without your funds for the length of time the bank is requiring. Ask them to, at the very least issue a partial refund until this fraud can be proven or dealt with.
The customers that give up easily, don't get their money back. Those that are persistent have a good chance at getting it back, especially for this amount. It's not worth a few hundred dollars for the bank to lose your business. After all, I am pretty certain the bank could write off on their taxes losses like this.
Good luck.....I know ...it Sucks!