Unclaimed Benefits lost

I had an unclaimed benefit with NMG. They acknowledged via email that all my details are on there system regarding my benefit that was not claimed by me as yet,. However the benefit details has been closed and they cannot give me any details as to what has happenened to me benefits. There offices are unreachable via telephone. There website is not operational. I only communicated with one consultant via emails. It has been two months of me trying to get my benefits from them. They stop corresponding with me despite numerous emails I sent. This is the worst experience I ever had with any company.