Need letter for new job

I am currently registered on the Operating Engineers Union out-of-work list. I'm on the B-list now and I was told I would go to the A-list if I could get a letter from my old employer. The union requires a simple letter that states the equipment operated and the hours on the piece of equipment. My old employer has been giving me the runaround. The G.M. is never there and seems to always leave his Nextel on his desk.
Q. Is there any way that I can force them to give me a letter? What can I do if they continue to resist?