Breach of Contract

I paid for a 4mb line but this December I was cut uncerimoniously to a 2mb line. I called the call center to find out why this was done and all I've been told is to wait 14 days for feedback on my call resolution. Why is it then that I need to pay my full December bill for a service that I never was offered. I was told a technician wud call me but not a single call whatsoever, This service is deplorable and I would want a refund as this is a breach of the contract that entered into with Telkom.