Normally if you are receiving nuisance calls you have 3 options to select.
1.Use call block facility (dialog gives this i am not aware of others check trough hot lines)
2.inform to your network provider via fax or written request (in dialog,if nuisance caller is a dialog cx, company gives a warning)
3.Final and best thing, Lodge a complain in nearest police station with all details.they will get all information trough a court order and assist you.
additional
For dialog customers , you can dial #107# ---> go to call management option----> Call Block
* you will be charged RS:30/= + taxe sper month