Cell C
Cancelled account but still was debited

I had cancelled my cell c speed stick account, a month and a half ago and was still debited this month, after complaining on hello peter and calling the call centre numerous times trying to get the contract cancelled in the first place, they eventually did it, however I was told on my last complaint that someone would contact me but they did not.
now I get billed for a contract that is no longer existing, after calling the call centre I was told to email a bank statement and a copy of my id with the amount that was debited to Cellc customer service and explain to them that way that I need a refund.
they cannot find the amount that was debited and I am still awaiting a response, can someone hire a person that can actually do their jobs properly.
I am awaiting a response this time Cell C!
thanks for my money!