Terrible network bad customer service

I recently took out a mtn contract for home 10mg line lte and I'm having no joy.i work from home and can not utalise the wifi. Nor can I stream anything cant even video call. I called the contact center who advised I can change my speeds at any mtn branch which I did on Saturday 26th March and was advised that I can not change package and speeds. Maybe after three months. No guarantees. I fail to understand how mtn expects me to pay for 3 months with something that doesn't work still expect their money come month end yet I can't even do my work? I want a urgent call from higher management someone whom is going. To give solutions not pass the buck. This is unacceptable and I feel they cna just come and collect their router and cancel this contract I can take my business elsewhere. This is totally unacceptable my details are as follows MTN line number is *** Randy Van wyk ***