There are people who I met on the field in Cape town,they told to join their thing and I'll get free vouchers they didn't tell me that they're doing debit order under my name and every month it's deducting 160

There are people who I met on the field in Cape town,they told to join their thing and I'll get free vouchers they didn't tell me that they're doing debit order under my name and every month it's deducting 160.I tried cancelling it and asking for refund but they haven't helped the only thing they said is that they cancelled it but it continued to deduct money on my account today.