Unauthorised Debit Order

These people basically debit our accounts without authorisation and then claim that there's something called voice or over the phone authorisation, problem is, they never called me to do this voice/over-the-phone authorisation, how is this even legal? They claim to be collecting on behalf of their clients which is other companies like KMA Marketing and Rethink RG and such. whom i don't even know as well, so basically i could call Paytoza and claim that So and So is my client and i want you to debit their account on my behalf and they'll do it without the account holder's approval. this is *******, someone needs to stop these people.