Selfone Cotract

I upgraded my contract last year October and received a faulty vodafone tablet I took it back within 7 days and the replaced it with the same model that was also faulty I did the same with the second tablet I also bought R700 extras after several trips to Pta West Auto page and Phone calls and E- mails I did not received any feedback. I requested to cancel the deal because of poor services delivery but are forced to Pay for something I did not received. I do not want the vodafone Tablet.