Billing a terminated account,refusing to sort out

I phoned Auto Page in February for an upgrade & they promised to deliver a new phone. End of March a debit order went through,I was billed on a device that I never received. I phoned the call center & upgrades department to find out what were they charging me for,to my surprise I was told I was charged on the new phone that I never received. Ever since then I've been wasting my airtime and time phoning the call center on this matter with no help but my account being debited. I got hold of a guy in the upgrades dept. who told that it was their mistake & the device was sent back to Auto page (to my surprise they knew where they send the phone at the first place)and my account will be refunded and contract terminated. The contract was only terminated in August but still the accounts is billing me on a terminated contract.l am tired of calling Autopage every month on this matter. I just want Auto page to refund back all my money from March & stop debiting my account. I ask myself how many people have become victims to such bad and unprofessional service to a so called big company.