Just lie...do not give them your correct number
So ‘accidentally’ changing a digit isn’t lying?
So far, I’ve managed to just NOT do business with them. That has seemed more useful.
I always give an incorrect phone number or ZIP code to places that ask for one. I also use frequent-shopper cards that are issued to another name. Probably doesn’t really do much good, especially if I’m paying with a credit or debit card, but I like it.