Axxess won't allow me to cancel my month to month service

I wanted to cancel my MTN service with Axxess as the line was dropping constantly, when I attempted to cancel the service I was offered a discount for 2 months I accepted this with the intention of cancelling after the 2 month period I then attempted a cancellation and was told I could only do the cancellation after 2 months with no option of future dating it, I was not informed of this when signing up.