Telkom LTE - a bad deal

I have signed Contract with telkom mobile for a uncapped LTE service, when it started it was great, one month we use all our data and went into the soft capped mode, it rendered the service useless as nothing could be done with it until the new month came around with new data. Since then our service is so bad everything buffers and we can not be two people on the net at the same time on you tube for example, i tested the line speed when we got it at first and it went up to like 50mb per second fluctuating up and down, now it is hardly 5mb. They changed the product with out consulting, i want to cancel this as it is not what i agreed to pay for, they said i must go to LTE as it is MUCH better than the 4mb adsl i had, it is now much worse! Sort the linespeed out or cancel my contract!!