IMEI - ***

I purchased a tablet at Pep Stores in Overport on the 22/1/2016. Before end of Feb the phone gve endless problems and eventually took it in to Pep on 8/3/2016. I have lost my invoice and due to this MTN is refusing to sort my cellphone and demands payment. Pep Manager is unable to get hold of MTN Rep since then amd MTN has advised that they are not responsible if invoice is not provided. Am I the first customer to lose an invoice? Surely the fact that a Journal reprint is available from pep that should suffice. I have been moved from pillar to post. This is obsurd! This is such revolting service! I need assistance asap