Bad Service from MTN East Gate

I had a cellphone contract with MTN which expired in 2016 and requested to be moved to prepaid since I was not interested in upgrading. On the 5th March 2018, I went to MTN store in East Gate to apply for a new contract phone. On the 6th March 2018, I went to the store to check if my application was approved or not. I was told that the systems shows that I owe money on the previous account, therefore they cannot approve my application because of the money owed.

I dont understand how I can owe them money when the contract expired and when I was moved to prepaid. Why was there no communication that im owing? Is it even possible to be moved from contract to prepaid when your owing money?

The service I received is very bad and I dont think I will ever use MTN again

###Dissapointed