I have been faced with this same situation twice over the years, once with a stockmaker, and once on a complete build. In both cases the work took maybe 8-10 times longer than originally promised. In both cases the work was being done 1000+ miles away thus visiting them was not really an option.
In both cases, my solution was to make myself so much of a pain in the azz that they couldn't wait to get rid of me: call in the morning, call at night, call at lunch, call on the weekend. Tell them you told me X, please explain again why X isn't happening? In both cases it took me months of effort, but I eventually got all my stuff back, and we are talking about thousands of dollars of potential losses.
Good luck, yes it is very frustrating.
