CELL C CHEATING CLIENTS

On the 20th April, I paid an account balance to close off the contract I have with Cell C, my email stated clearly that my reason was that I cannot afford 2 contracts anymore but only 1, I paid the balance & even got the email confirmation with ref no of my amount allocated successfully, last month the 25th I was debited again for the same account & when I call for querying, I am even told that I will be debited again this month, my email to request for settlement amount was clear"TO CANCEL MY CONTRACT". THIS IS NOT FAIR AT ALL