Can't Get September Invoice

I was on contract but cancelled it early September. Since then I have been waiting to receive an invoice so I can submit a claim with my employer to settle the outstanding amount on the account. I have been sent from pillar to post with some people promising to email me the invoice but instead sent me a statement. Vodacom wants me to settle the outstanding amount but is unable to produce an invoice,this is a catch 22, I need the invoice!