On an Android smartphone you can use call control to block calls and texts from any number. I have used it for over 6 months and it works!
Just google "Call Control" or look for it in an apps list. Free version available, but the low cost pro is much better.
Canadian pharmacy. Relentless and complete lack of respect for my request to be removed from their calling list. They specialize in selling pharmacological drugs at the cost of their own dignity and self-respect.
India based pharmacy saying they are a Canadian pharm......they will not stop, changing your number is the only way. I have chatted with people on different forums that have been harassed by them for 5 years or longer. I went to a marine store and got a small (but powerful) air horn.....fits in your pocket. When they call I hold the phone away from my mouth and talk softly so they turn their headset volume up, and then a good 5 second blast directly into their ear. I still get the calls but now they are a lot more fun!!