Vodacom not allowing me to close my account

So my Vodacom contract ended in May and now I want to close it. I call their number and when I reach a call centre agent and before I can explain why I'm calling, they hang-up. I tried this a couple of times and now my number is blocked.

After this, I go to a Vodacom-shop, and I explain the situation and we must call, so we call the call centre, and they hang-up on the Vodacom-shop employee. We try a couple of times and the same thing keeps happening. So he says ***** it, I'll open a service request. He does that and I get an SMS, so I go home, the following morning I get an SMS that my issue has been resolved.

How is this possible? You are a service business, this is not how you retain customer loyalty. I have learnt my lesson, let me go.