MTN & Mondo customer care bad service

I signed up for a contract of a laptop and a router, I recieved the devices but the laptop is super slow for a new laptop (I know and understand the specs), the router never connected since. These devices troubled me since I received them. I made calls & emails to both MTN & Mondo no one could assist me. A month later after complaining I recieved an email from MTN informing me that my application is pending, that time I had the devices for a month. 2 months after I had a call from one of MTN consultants who informed me that they will arrange to get me a new laptop and the router and I'm still waiting till this day. Last month I got another call from a different consultant and told me she will escalate this matter and send me a ticket number, till this day no one called. Now my MTN bill is piling up and there's no way that I will pay for the devices that are not working, and this is affecting my great credit score so bad :( !!!