DISGUSTING CUSTOMER SERVICE

I am very disgusted by the service received from Cell C and is never using them again... I had 2 contracts with them, 1 on the cellphone (Huawei P9 lite) and a sim card data contract.....time came for my upgrade and a lady called to offer me the Huawei P-Smart, i then told her i don't mind upgrading but i need the sim contract to be deactivated or the service i was receiving from the sim card should be transferred to the new upgrade, she said that wont be possible but cancelling the sim contract will be done.....OK that is fine, a month later i call to find out why the service hasnt been cancelled, i am told that i was supposed to call in and cancel it...but that's not what i was advised.....i tried cancelling and been transferred from one person to another with no luck. So months go by and i am not receiving the services and no money is being deducted from my account so im thinking FINALLY it is cancelled.....to my surprise early this year i receive threatening calls and emails from lawyers stating that i owe Cell C and my account has been handed over, i call CellC and they advise that my account is up to date and i owe them nothing, i should also ignore the threats. Last month i received another call from their lawyers saying i owe them R700.....I am very angry at Cell C and I want nothing to do with it......Cant wait to finish this damn contract and part ways. I will never use them in my life