False Advertising - Great data deal - Useless Speeds!

I recently got the 1000GB Fixed LTE deal and it all worked fine for a couple of days... I got 35 Mbps and up on my download. Now all of a sudden after using it for a bit, the speeds have been terrible. I need to restart my router every 10 min to get another IP address to fix the speed.

Then after 10 - 15 min the speeds are garbage again!! This is not MTN Business SPEEDS.

There is no issue with my router, because I use Afrihost as well, which is on the Mtn network and their speeds are great.

It's not coverage /Signal either - BECAUSE I have another Mtn SIM card in my cell phone and the speed is perfect.

I want this resolved ASAP or I WILL cancel it.