Standard Chartered Bank — charges or penalty on non payment

Address:

560102

My credit card tagged to amazon account who used it to subscribe for kindle account without my authorisation who eventually reversed for 3 months (Dec 17 to feb 18) in the month of june. Meanwhile i never followed sc reminders to make payment and was thinking tiny amount would be bank charges but it got my attention when june statement asked me to pay 1.7k in total though i never used my card. I place the request to review my card usage (Nearly 9 times).in an effort to protect my credit score i made payment of 1.7k in june and in august they sent an sms confirming they cannot waive anything but most annoying part they charged additional 4k from june to nov on the same amount as penalty which i consider heights of taking customer for granted.
I spoken to rm and gave all historic emails but received an email yesterday stating they cannot help on this matter and shared invalid email address to share my concern.
In short - i asked to pay 6k amount as penalty for not using my card and raising my concern time to time by calling customer care. Not sure how we can legally sue sc