Bad servise

I paid my account last weekend at game I was surprised when I received a call from one their collection agent she was so rude and threatened me that she will do something with my account. Today my account is blocked I can't even make a call. I'm on my way now to Cell C to give the proof of payment. Is not he 1st time I report Cell C with their client service how their agent are treating customer unfairly. I want to get done with Cell C I've been having different contracts with Cell C, but still they are not doing better with their services.