December Invoice

My cellphone contract ended on the 30th November'15 and now I am on prepaid. I requested a December invoice so that I can settle the account. They told me that my contract has been deleted on the system they can only provide me with the statement which I haven't received by now, but still I can only pay as per invoice so that I can see what I was billed for. The call center consultants they kept on rounding in circles, no one can provide a tax invoice and was told that if I don't pay they will hand me over. How can you say I must pay but you can't provide a tax invoice? I hate VODACOM!!!!