You've called me a few times and I don't want to return your calls.
Seriously? Why won't you return my calls?
I received a call from you three times in a row and I'm tired of ignoring it.
If you don't want to answer calls it's ok. You don't have to be rude about it.
That's how I make people feel when they interrupt me.
You don't have to want to call someone back, but it would be polite to answer and tell me to stop calling. How would I know if you don't tell me?