Consumer Redressal

I have made a payment of my Citi bank credit card via ICICI bank net banking facility called \"Pay any VISA card\" on 4th September 2013 and its been over four months and they are yet not able to track my payment and are charging me interest over already paid amount. I have furnished them all the proof of payment including bank statement and ARN number etc that I got from ICICI bank. But there seems to be a lack of effort from Citi bank to resolve the issue. Please help.