Cancellation of Wi Fi Router contract

I have cancelled my Wi Fi Router end May and confirmed with them that my last payment will be end of June. I phoned on the 2nd July just to confirm the cancellation went through only to find out that it never happened. So I cancelled it again. On the 11th July I got a call from their sales department trying to get me to upgrade another contract. I asked this person how many active contracts are showing up on my account. You guessed it, my Wi Fi router still showed as active. He put me through to their cancellation department and a guy assisted me with the help of 1 of their supervisors. So now it shows I've cancelled this contract only on the 11th of July and not the end of May. So yeah, Cell C now wants to force me to pay another month's usage because the cancellation date shows 11 July (even though I haven't used any data at all for the month of July). Today, 20 Aug, I asked to speak to a supervisor and the lady informed me no one is available because everyone left ( this was just before 15h00) On other calls I also asked to talk to a supervisor but they seem to be non existing. I asked for my signed contract and they sent me another guy's contract instead. I phoned again and today they sent me a renewal contract for my Wi Fi router! So I phoned again and now I need to go to the shop and request it and if they can't help me I need to send yet another email to CellC. BTW, those security recordings is the property of Cell C and definitely not for you to request when you have a dispute. I will now take it up with legal council. I'm just really frustrated that even though I'm a customer of over 10 years they treat you like ****. I am very disappointed and will think twice before upgrading with them going forward.