airtime debit on my account

I have an Edgars account and around September i have noticed that the have cell C airtime that i have never received any communication about them offering the service to me.Upon inquiring about this they told me that they use secondary number which is my brothers number and they send a link to his number and apparently they he pressed yes to accept their offer .But now my issue is that i am the account holder and money is taken of my account and they have my contact details but why choose secondary number not mine. When i asked my brother he told me that he has never revived any airtime.