Bad service from MTN

I took the mtn wifi router with uncapped data on contract. It worked fine for the first month. After that i had problems every day. The 1st week of August my internet was nonexistent. I phone them everyday with no luck. Its now a month later and still the same. I am suppose to have a 10meg speed but at night its running at 1, sometimes less than 1.i do not know who to phone anymore, they keep telling me the same thing. Please helopeter help me. Thank you Nicolas Thomas