[honeychile]

IMHO, the two best methods to use which still leave some dignity to the situation are:

1) Ignore the calls, but if confronted in person, smile but firmly state that you no longer have the time that this project deserves.

and

2) The broken record method: no matter what, just repeat the same phrase. Example:

Person A: "You said you would do Project X!"
You: "Yes, but I no longer have the time to give to this project that it deserves."
Person A: "But you promised!"
You: "Yes, but I no longer have the time to give to this project that it deserves."
Person A: "No one else will do it."
You: "Yes, but I no longer have the time to give to this project that it deserves."
Person A: "Do I have to do everything?"
You: "I no longer have the time to give to this project that it deserves."
Person A: (no matter what is said)
You: "Yes, but I no longer have the time to give to this project that it deserves."

I guarantee you, it will work every time, yet there is no screaming or bad manners on your part!