Abusive relationship with MTN

I have an MTN router and data contract with them. Summary of the contract is that I pay monthly subscription and they provide me with data. Since the 1st August 2018 I am unable to connect to the router (wifi) in the house and the error is no connection. I called their call centre and each time I am told that they are unable to assist me. Eventually I went to Mtn shop nearby and they gave me another number tAo call. here I was given a call number and told the error will be resolved within 10 days.

They say it is a network problem, but I am paying for a service they are not providing

I am supposed to get monthly data credits on the 14th and I have not been able to use the previous ones. This is such an inconvenience to me as I had to buy more unplanned data for my phone. I would also like to cancel my contract with MTN as they are not providing me with what was agreed upon, their call centre agents are of no use and keep on dropping the calls.