MTN Business black friday no no

My Simcard has been loosing connectivity from day 1 since I got it with thie router . IT would randomly disconnect. I have asked a colleague of mine and he does not have so many issues . I took a black friday business deal out for me to work from home but this has been an utter nightmare I do have coverage where I stay but the random disconnects and reconnects must stop the Router shows its connected but I get page cannot be displayed or internet time out I sometimes get 0.79 with a high latecy on the speed test or sometimes 2.01 Meg up and 0.5 down the worst as compared to vodacom. What can be done about this and also I am not receiving my invoices on time either . I am still waiting for my invoices to see how much must I pay because now it looks like the account is behind and I am being throttled Please advise as I cannot work like this I really throught 100GB any time data would help me with my studies and work and now I am too scared to continue as the network may decide to loose connectivity in the middle of the exam.