***** on my account

I received an sms that my number has changed without my consent, called the call centre and they were very unhelpful. Few minutes later balance in my account has changed, called in again and was told there was a purchase done. They requested my ID number and I Would never give such info over the phone, what annoys me the most is that a ***** star can walk into your store purchase and change cellphone number without my ID but when I call to report this I cannot get help yet a total stranger can be given my entire portfolio