Harassment of people on my call list

I loved being a Cell C customer....until I tried to end my contract! I went in explaining that I was emigrating & wished to cancel. I had to pay for the remaining 7 months PLUS a penalty fee. I paid cash. I was assured that it would end at the end of the month & no more payments would be debited. My account was cancelled within 1 hour so the remaining 3 weeks I had no airtime that I had already paid for. Now, 3 months later, they are still trying to debit our account - we had to put a stop on the account. They retrieved the phone number of my FRIENDS off my call list I assume & are HARASSING them with sms's for us to pay. This is an invasion of privacy & not mentioning that the account was cancelled & paid up 3 months ago!! Who is incapable of doing their job? I asked if this would happen & was assured that it would not. (My daughter is having the same problem with Vodacom for 18 months already - hence my stopping the debit order at the bank). Why do they expect you to pay twice and harass my friends - it is unacceptable and very 3rd world!