The only way you can block a number is with a phone, or separate call screening device, which has those features.
Changing your number might bring its own set of problems. Any 'new' number will be recycled from a pool of numbers allocated to VM. If you are lucky, you might get a new number which has had little nuisance activity on it in the past and has remained in the pool for a long time. If you are unlucky, the new number may have its own previous nuisance history or may have been previously used for business activity.
Changing a number may be useful to break contact with a specific person rather than just general nuisance calls. Blocking an individual number, for an individual person, may not work as the unwanted caller may just call from a different line.
I use this device for dealing with general nuisance calls
https://www.truecall.co.uk/category-s/116.htm
which has very effective features for screening and blocking unwanted calls.
