I read or heard somewhere that phone numbers are supposed to be out of circulation for 6 months before being reassigned to a new line - to avoid situations like you are describing.  Unfortunately, companies don't seem to want to abide by this, or they don't have enough numbers in their inventory to wait 6 months before re-using a number.... so you get calls and texts intended for the previous owner of the number.

If you haven't had the number long and switching would be less of a hassle than all the unwanted communications, you could try another number.  It may or may not be an improvement.  Change your number at the start of your next billing cycle to avoid prorating... and you can change it due to harassment without a charge.