MTN - upgrade false advertising

I upgraded my contract with MTN via their affiliate Mondo on the 1st September and received my device a few days later, but it was the wrong device and also suddenly the contract was changed to 36 months and not my normal 24. I returned it the next morning which was within the indicated time period in order to reverse this upgrade - this is also my right under the consumer regulations. It has now been 3 months and it has still not been reversed. I am paying for the contract and device as well and cannot even make a choice of a new upgrade until this has been sorted. Absolutely shocking!! In the least I would have downgraded to a sim only contract until I decided on a new phone... but I am paying for a full contract!!! TO think I have currently got 9 lines with them....