Do I have a legitimate fury??

Good Day In the beginning of the year, I realized that I have been paying for a contract that I haven't used for a couple of years (yes years, with all my deductions I missed this). It was a tablet my son broke while skating. I phoned Vodacom from my pay-as-you-go number to cancel the contract, just to be told I cannot phone from a pay-as-you-go number to cancel a contract. I must phone from a contract phone. I then went to Vodacom Canal Walk to cancel after hours, just to be told I cannot cancel, I have to phone in and they cannot help me because it's after call center hours. How compliant is this for customers? Because it was a busy time for me, I then just cancelled the debit order. What I remembered from Debit orders is that that it is considered cancelled after two consecutive cancellations. Now after more or less six months, I have been given over to debt collections for R900 due to them. I asked for explanations on this but am still waiting. Before being given over I spoke to Vodacom explaining this to them and they promised to investigate it. They promised to come back to me. Nobody came back to me except the debt collectors. When I had a number on a spare phone, they took the number back because I did not use it, but they yet, they were blind to see this contract number was not used. I told Vodacom they can check this too. The contract was on a month-to-month basis for years and not on the initial two years anymore. Am I missing something or is this just how business is conducted? They told me that they could see on the system that I have not used it for years. Let me not for this, while I'm challenging all this, they could phone me to my prepaid number 3 weeks ago or so ago for an upgrade on my said contract, but I could not cancel form my prepaid number. How utterly ridiculous is this? This was also, I was told, recorded. Thanks for your time.