Credit cards cashbacks is only for initial users after long usage, your whole finance history and personals data stored by the company for business usage and other's marketing offers. if you are average earning person, stay away with credit cards emi loans installments .
Most important that never apply credit card from those shady companies will make you regret in future about loans and high expenses valid with their credit card.
Try to use debit cards and rupay cards. If you stil want to buy from emi only try to ask bank.