FNB ******** ME OUT OF MY HARD EARNED MONEY

I called FNB to pay off a loan that was suppose to end in December. upon Calling the person loan department, I was assisted and they loan was paid off. However double the amount I owed on the loan was deducted from my bank account and no one seems to care about giving me my refund. Im told to call again tomorrow or wait and they agree that the error is on their side for the double deduction but no one is giving me a clear answer of when Im getting my refund. I have been with this bank since high school, through university and now Im working, Im soo disappointed and just feel ****med. I really think its time for me to switch banks.