Telkom stole my data

I cancelled my LTE data plan at the end of November 2016. A month later, in December, they debited me what I thought was my final debit (After my 1 month's notice). However, I was debited again in January and after asking why, they said I had used data in December...even though my LTE router was not even in use from the beginning of December. They then debited me again in February, two months after my contract was terminated. I have been passed from pillar to post trying to get this resolved and I want my money back. Do not do business with these *******.