Worst telephone network service ever

I had a router contract which ended in February 2023 and I sent a cancellation email,they didn't cancel it and they said I must call them, upon calling I never got help and the next thing they sent a SMS saying I owe, I went to the branch Protea Glen Mall enquiry and they never helped me, they were always saying the lines ain't working. The branch assisted with opening the contract but failed to assist with cancelling it. MTN now handed me over for collections, how do I pay for something I haven't used and of which it's contract ended. MTN please terminate this contract and clear my name.