Worst Call Centre Ever!!!

i have been behind payment with Cell C and for months i have been trying to contact you, each time i call i hold for more than 20min (with my own airtime from another network provider as you switched my Cell C sim card off), first i go through to collections and i'm told that i'm handed over, and then i'm transferred to your legal, when i get there i'm told i'm with an external company. When i speak to the external company i'm told that they cannot pick up my details.

Who must i speak to if no one wants to assist me , i am behind my payment and i want to make arrangements but no one is willing to assist.