Kotak Mahindra Bank — credit card fraud issue

Address:

Surat, Gujarat, 395023

Kotak bank executive manager my name is mehfuz hasan, last month i offered from kotak mahindra credit card bank executive 26th march 2019, it is per-approval credit card with credit limit 50, 0000. Than i received credit card 5th april 2019, my credit card was urbane credit card than i contact to kotak executive to upgrade it, they offer me kotak league platinum credit card and it also credit limit was 50, 000 this card is lifetime free and first time chargeable 1500 + 270 gst. After that on 19 april 2019 they are message me that your credit limit has been reduce from 50, 000 to rs 15, 000.
In between i used my kotak league credit card and they have been charge me over limit fee 500 + 90 gst.