Also remember to check your device. as was pointed out earlier, TM LTE wont work in any phone.
There are also other fun loopholes.
I have an S4 GT 19500, its not LTE, But it supports the 1900mh/z frequency that MTN uses.
I called MTN and made sure my SIM was LTE capable, and activated (loophole they don't tell you about in store) on the network for LTE. once I got all of that set up, I sat down with speedtest my phone and an MTN S4LTE Gt19505 that a friend in the office owns.
He also activated LTE on his sim and did everything correct, I did help him get it all sorted.
IN Sandton bot of us sitting next to one another got exactly the same speeds, if his phone shows LTE, and mine shows H+ we both get 18 to 22mb/s download and 6-8mb upload.
There were cases where the speed drops, I mean it is a mobile network, and we did run loads of tests to get it all averaged out. the best speed we saw was a 38mb/s download, that was on the LTE phone, while my phone timed out on that same test, so I am guessing he somehow got insane priority and just killed everyone's connection in the area.
the average we got was around 14mb/s download. and that is consistent on both devices, LTE and non LTE.
Why did I explain all of that? a non LTE phone is cheaper than an LTE phone, and MTN gives you access to Afrihost for data prices. Abuse the loops!