WiFi Cancellation

I was informed my mtn WiFi contract could be cancelled at any time as it was a month to month contract. I was also informed to bring the wifi box back to the the store where I entered into my contract calvinia Northern Cape. I did as was informed and was told to sign cancellation forms and that I would receive a reference number upon the cancellation of my WiFi. I still have not received my reference code and I am still getting messages that my monthly data for the WiFi has been allocated.