wells fargo bank Took out $500 from my account from 9/24/12-11/20/12 to pay back a loan of 500, details were not clear, Internet

I borrowed $ 500 from the bank on 8/24/12. I received a letter stating that instead of them taking out all of the 500 at once on my next payday, I could use their slower repayment plan and pay back the amount over a longer period of time. I called the bank, spoke to a young gentleman about this program, he never stated that everytime an amount over $100 comes into the bank, that they would take it out and apply it to my loan repayment plan. So what has happened is they have taken out 100 from 9/24/12 - 11/20/12. this amount is equal to 500. they took out 100 on the 19th of November then turned around and took out 100 on the 20th when i got paid. I have told them over and over in e-mails that this is not right and please return the 100 back to me, especially sine they took out 100 on the 19th. All responses are that the account is "set up" to remove the money" and they cannot return it to me. Also they start the statements about how I should have known from the loan paperwork that this would happen, and their "Sorry" that I was not informed when I applied for this repayment plan. After speaking to the gentleman in the begginning, I expected to pay back this loan every payday, as that is what happed when I borrowed the 500 in the past.