Contract termination

Good Day

My Name is Constance Mokoena and I had contract with MTN which I settled last month. My reason for settling the account is because I lost my job so I did not want to have a bad credit record or ruin my relationship with MTN since they have been good to me. Now I went to MTN store and they told me to pay R11 200 in order to settle my account which I did but today I recieved the airtime and data that I used to receive and when I called the customer care I was told that I havecto pay my installment. Please help me as I have not used any of the data. My cell number is ***