Harassment Call from SBI Credit Card

My husband had SBI Credit Card, once he had dropped in cheque against credit card dues in SBI Branch where they do not have credit card cheque services. He was unaware of that and he didnt check his statement. The next statement received with late payment, fine and service charges on Rs.1600/-. We cleared that due of Rs.1600/- but requested them to reverse late payment and interest on that. They reversed late payment charges but not interest amount. The fine amount and interest accumulated to the tune of Rs.16000/- when we contacted the Branch Head for surrendering card and waiving off that interest amount they waived of 50% only. My husband had agreed for this and signed their letter and made cash payment of Rs.4000/- and requested time for balance payment. Due to some financial problem, he could not make that payment. They started calling me frequently and I requested for some time. Now, without informing us they reversed this amount and sent us statement asking us to clear the dues of Rs.17965/- . As my husband is working in hospital as O.T.Incharge, sometimes he would not be in a position to attend calls and they call and harass me and say why your husband is not attending the call, he has not cleared his dues, is he unemployed or is he absconding, such questions hurt my self respect, and disturb me during my working hours. If I tell them to call my husband after 6 pm, they would say our working timing is till 6 pm.. On behalf of my husband many times I called them to waive of the late payment and interest charges that time they told me only the card holder has to call. For recovering why they call us. Just for Rs.4000/- they are again threatening us to make payment of Rs.18000/- otherwise my husband name will be listed in CIBIL as defaulter. Kindly advise me, as my husband has no dues against purchases, eventhough we have cleared latepayment and fine charges to the tune of Rs.6000/-.