Barclays Credit Card
Charged with Late payment charge despite making payment on right time

I have a credit card with Barclays and facing a issue that I have been charged with late payment fee despite making the payment on the date required.

Bank is saying that I should have dropped the check at least three days before the last date which I cannot as I was out of town at that time.

Please suggest if bank can apply late fee charges even if customer is submitting the payment check before due date.

complaint reference number with bank is 20080910610300.

Please suggest what best can be done to force the bank to reverse those charges.