IGA INVEST ILLEGAL DEBIT ORDERS

I am ****ed beyond, on Saturday i received an sms from IGA INVEST claiming that they will debit R98 from my account on the 31/07/2018 from my account. I have never agreed to anyone about anything over the phone. I then called their call center yesterday asking what is happening... The lady informed me that the reference number on the sms was not for me and that they will not debit from my account. This morning they debited from my account without my permission. What further measures can i take on this company who is illegally taking money from my account.