Unauthorized collection of funds

I opened two cellphone contracts on 9 October 2021. I paid for the activation fee and was told that that was the only fee involved. 3 days later I was charged R327.26 per contract - a total of R654.52. I was not emailed any bill to confirm what this debit was for and received no communication from Vodacom. This was an unauthorized collection from my bank account and it needs to be refunded.