ICICI Bank — unauthorised credit card interest charges in september 2018

Address:

500085

I k balsingh, bearing card no. [protected], i called to your customer no and asked for redeem cash reward point to september month payment as rs.62000 appx, balance amt payment suggested by customer care personal as rs.60378 adnd dropped cheque before due date and credited redeemed cash as rs. 1716 on 24/9/2018. October payment as rs. 7338 in that i spend only rs.3800 appr. But how it is rs. 3500 interest charged on no amount balance amount left over there. For this i contacted customer care personals but there is no solution has given to me and due date as 8/10/2018.
Regads
Balsingh