Mtn going from bad to worst!

I am at a lost for words. I paid my account in advance but still they suspend my line. Now they want me to send proof of payment but I paid at a Mtn store. Sad thing is this is not my first complaint of them and I am sure it wont be my last! Aaaaand that is the reason I cancel my contracts with them as they expire. Utterly dissatisfied with Mtn!