I would love to know if they ever where going to put a bell up.
If I had time/lived nearby, I would have employed the world famous "LurkingHusband" cheap trick :
Turn up at store (ideally dressed as a contractor) and announce
"I'm here to fit the bell."
When confusion arises, you insist that you have been sent - by head office - to fit a bell. As the debate progresses, you quote from the discussion here, saying that you were told by Thorntons head office to make it a priority.
Basically, you need to push Thorntons head office onto a dilemma. Either:
a) keep schtum, allow bell to be fitted, and make a note to never tangle with the Lurking press machine again
b) admit that all the correspondence this far was wasting everyones time, and they had no intention of ever fitting a bell.
The whole exercise has much more effect when the "workman" arrives with the local reporters (it can be amazing what a mate with a camera can do for appearances) to write up the "aren't Thorntons amazing ?" piece for the local rag.
(One day, I will detail how my Dad used the inherently racist nature of the Tory party to swing a 10 foot extension in the face of universal opposition. 
).