Don't believe what virgin mobile champs tell you

On 23 June 2015 I spoke to a virgin champ. He explained what I needed to do to terminate my contract. I followed his instructions and one hour later had paid the money required to terminate the contract into Virgin mobile's Nedbank account. In Oct I was sent an invoice stating that I owed R19.60. I phoned and spoke to another champ who told me this would be sorted and I would hear back from virgin mobile in 7 days. I never did. In Nov I got another invoice stating I now owed R378. I phoned again and was told the contract would be cancelled. Each time I phoned I went through the whole story, I got told it would be sorted and then...nothing happens. Is this a virgin mobile policy? During the call today, I asked the champ to forward me the email he said he had sent to the billing department detailing that the contract is cancelled and whatever amount was incorrectly debited would be credited...but the champ said this was not possible because the email he sent is internal business. I then insisted on getting confirmation in writing. I have been told I'll get this. Given previous experience this seems unlikely. Evidence this far suggests this will go around and around in circles.....