My key fob is not working

I can only open my Omega car door by the key as the remote system is not working, but can open the boot, sometimes the car starts but many other times now it wont start, after waiting for about an hour it sometimes starts, recently it has not start all, called the AA but could not get it started, towed car to the garrage on getting there it starts, took it home wont start again, please what is the problem and what im I suppose to do.
Thanks