The language used in the CC issue form can be tricky. It might have been mentioned that terms and conditions expressed herein and all T&C introduced from time to time shall be applicable/acceptable.
CC companies also cite MITC which are posted at their website; although in a contract any new T&C should be informed to each individual customer for acceptance and till accepted it can not become applicable as the contract is legal. Banks like Citi bank have started posting MITC along with all monthly bills. Banks/CC companies also claim their CCE call and update the customers.
However if bank has overcharged customer should complain to bank as per grievance redressal mechanism, MD, Chairman, and then if no resolution /relief is delivered customer has the option of approaching the institution of print and electronic media ( the idea is to tame and shame the bank), legal-consumer-public-social portals, RBI,BO, DCDRF, police, courts of law, Lok Adalat etc.
You may search the previous decided cases at Confonet
confonet.nic.in/
and establish that bank is a habitual offender.
A determined customer may contemplate to charge for criminal breach of trust, forgery.
Some of the consumer help organizations have been doing good job e.g.
pehredar@network18online.com
https://www.facebook.com/Pehredar
www.grahakseva.com/
www.creditcardwatch.org
Credit Card Holders Association of India
https://www.creditcardasson.org/RBI%20guidelines%20on%20credit%20cards.doc
https://ashisha.com/consumer/
Let your lawyer handle the matter.