Roaming charges dispute

I am having a problem on my account with regards to data roaming when abroad. I switch off my roaming when leaving south africa and get a bill for charges. This has happened to me on previous occasions and have logged it with vodacom. I have screenshots with everything off, sent and showed it to them and still get a bill for usage. I have spoken to vodacom accounts and told them that if I have to pay this account for something I didn't use, I will cancel my contract with vodacom and I have a VIP account with them... and their response to me was... can I give you the number for the cancellation office? What the hell???