Deductions from my account and never gave permission.

I was contacted by Telkom mobile in December 2017 regarding a contract for the internet. The total cost was R749. this took place on the 15th of December 2017. I had a deduction on the 22nd of December 2017 for R55 and this month from them and I see the same deductions have taken place. When searching the internet on these deductions i see it ***** because I never gave permission for them to deduct these. I want my MONEY back. ********.