Cheating in full and final settlement of credit card

Location/place: new delhi

Name of company/service: icici bank credit card

We (me & ICICI Bank representative) negotiated on phone for the full & final settlement of dues in my credit card account.
We settled at Rs.45000/- (Rs. Forty five thousand only) in three equal installments of Rs.15000/- (Rs. Fifteen Thousand Each).Before i pay my first installment, i confirmed from their customer care office that if they have issued a letter for my full and final settlement & their answer was yes. So i paid my Rs.15000/- by cheque, which was debited from my bank account next day.
After two days i received a call from their representative, he told me that the amount which i paid cannot be considered as a part of full & final settlement as due principle amount is higher & i have to re negotiate by visiting their office otherwise this will create problems in my home loan (from the icici bank)whenever i make my final payment for home loan if i don’t re negotiate as the credit card & home loan taken from the same bank.
I hope you have understood my problem & expecting help from yourself.
Thanking you

Regards.
BALJIT SINGH.
Ph. no. 8527596511