account theft

My wife requested a settlement latter for her loan. On receiving the settlement letter, we paid it in full on the date stated on the letter. We then discovered that we needed to pay more as they are saying it did not reflect on time so it was not settled. We then paid that as well. On for the same thing to happen again. This is now theft as far as I am concerned as we paid it on the due date and in full. The account now needs to be closed and a paid-up letter sent to us. THIS IS NOT ACCEPTABLE AND NEED TO BE SORTED URGANTLY. IF IT IS NOT, WE WILL BE REPRTING THIS TO THE NCR YOU CAN CONTACT ME ON MY EMAIL AND I WILL SEND MY WIFES INFOEMATION SO WE CAN GET THE PAID-UP LETTER