MTN

I cancelled an upgrade with MTN within 3 days of doing it, was advised everything was done and I won't be billed. A month later I'm getting billed for a device I never received at all. Advised MTN of the billing and they advised I must pay the amount and will recevive a refund after 2 days of my complain. It a month now and still no credit has been passed and still getting billed for the device. MTN has no sense of urgency and they lie.