too many text per day draining my minutes

I received two calls from this number today. I was not home and when the answering machine kicked in the caller apparently hung up. Who is this and why are they calling me??

Have received many many calls...

offer optus prepaid package and asked for personal details such as name, phone number,date of birth.

These people call me 10 times a day My husband has to have my help 24 hrs a day 7 days a week I dont have time to answe phone calls when no one is on the phone They even bother me at night around 9 to 10pm when we are in bed

They call about every other day stating that they can see my credit card balance. I told them not to call again but they still do.