Slow speed and no report back

I took out a MTN Home Internet plan last year which came with a router. At first my internet speed was really good and it worked well. However, since November last year, the speed has been really up and down.

Despite several emails to MTN and computer generated responses that they will look into it etc etc, my speed is still shockingly slow, For what I am paying a month, I think its disgusting that I cannot get proper service or a report back on this. Really dissapointed!