What device are you using?
It is possible if your device has built-in feature of blocking a call or text from a particular number.
Other option is to download a call or text blocker app.
My friend also encountered this kind of experience, but unfortunately we can't request to block prepaid number.
try to block nalang the number on your mobile phone..
You have two options, you can report it to Globe hotline since you mention that even your parents receive certain messages save it or get a screenshot of the message just in case Globe ask for it. The other one, report the mobile number thru NTC, same procedure they will ask you the details of the messages and possibly a screenshot of the message.