Can't buy Data Bundle with Topup Airtime

I am on an MTN Choice Topup Contract, and receive R200pm airtime. At the time of signing up the contract, I was told that this could be used to purchase bundles (SMS, Data etc...).<br> <br> I have now carried airtime over and have about R540 according to 141. Everytime I try and add a bundle, I am told that I have insufficient airtime!? <br> <br> Went to a branch this morning, was told that it is not possible to purchase bundles with the included monthly airtime, instead I must add additional airtime and purchase the bundle that way. When I said that every single other network allows customers to do precisely what I am requesting, he told me that MTN are apparently updating their T&C to allow for this. <br> <br> I asked to be shown in the current T&C (as well as the one I signed) where it states that included monthly airtime cannot be used for data bundle purchases, and we were unable to find this particular clause.<br> <br> In short: MTN gives me R200pm to do with as I please (provided it is out-of-bundle surfing, smsing, calling) but do not allow me to purchase bundles with that R200pm. Madness!