Worst provider

This is the worst provider I have ever had to deal with. When you sign up everything is easy and straight forward. Try to cancel, different story. I had a month to month fibre contract with them, due to moving abroad, we gave notice in writing more than the 20 days specified on the form, also specifying the effective date for the services to be stopped. We were supposed to receive an updated invoice only for the days we used the service. We received a normal full invoice. After numerous emails and phone calls I was told that the service has been cancelled and a dispute has been logged for the refund. Now, 1 month later I am still waiting for the refund for September, and received a new full amount invoice for October with still no word about the refund dispute.