Refusal to cancel upgrade due to voucher

I have been attempting to cancel an upgrade which I did not give consensus to with Elite Mobile but to no avail. I confirmed clearly to Elite Mobile during the initial telephone communication that I did NOT want an upgrade and they assured me this was simply a re-arrangement of my package until I am able to upgrade. This was not the case. I received a voucher that I would never have used if I had known the true intention of the phone call. The only reason that Elite Mobile does not want to cancel my unwanted upgrade is the voucher which I offered to repay immediately or that the amount be added to my bill. Elite Mobile refuses and now I am locked into an agreement for two years that I never consented to. This a violation of the Consumer Protection Act 68 of 2008 (sections 14; 40; 41; 51).