Hi Moo's Mum,
Personally, I did not experience this, as I still have my gallbladder. However, a very close friend of mine has had that trouble for many years. Her doctor tried lots of things, and finally sent her to another surgeon who specialized in such things.
He put a stint in the duct (twice) in hopes that it would
open it up and stop the backup problem. (I believe that's what she said was happening).
I'm sorry to be the bearer of bad tidings...the stints didn't help (they often do, though, so don't assume it wouldn't work on you), and she's still having the same problem.
So...she has determined that she'll have to control it via diet, because she's sick of looking for a medical answer, because the docs seem clueless.
If you'd like me to have her write a first person explanation of what happened, let me know. I can write her an email and request more information. It might take a while, but I'd be glad to do it.
Sorry I can't give you a better answer. Thought you might be interested in my friend's situation. Actually it always amazed me that she could have gall bladder problems when it had been removed. Come to find out, it's a common problem!
Good luck finding a cure!