Fifth Third Bank 5/3rd Bank Future Interest Rate Charges for a Vehicle Pay Off , Internet

I contacted 5/3rd Bank to payoff my vehicle prior to term ending. They said I have to add on 10 days of interest to the final payoff amount. Even though I have funds available today and they can't receive payment over the phone or in person (there is no branch here) I have been penalized for the time it will take them to receive my payment through the mail. I asked even if the letter is post dated to today's date it still didn't matter.  This is bad business.  These people offer their loans through dealerships, online, and where ever else.  I went through a dealership. I was also am a on time never late client. I highly recommend with this type of auto loan to NOT get a loan through this business unless you want to pay for FUTURE INTEREST PER DAY UNTIL THEY RECEIVE YOUR PAYMENT.  (on average it took them 11-14 days to process my checks I sent them in the past).