Cell C poor customer service

I am appauled by the service that I have received from Cell C. I took out a 24 month contract with the entity for a Huawei P40 smartphone and I made the payments for the duration we agreed on. To my surprise, I got a call from their collections team informing me that my account is in arreas. How can my account be in arreas when I have made the payments for the contractual duration? Then I was told that my data was cut but the areas amount still kept accumulating, how does that even work!!

To make the whole experience even more bitter I am unable to cancel the contract until the I pay the amount that's in areas, which means the contract amount will keep going up even if I agree to pay a certain amount to the outstanding balance