maxitron G30-ZRHSO not working?

I got an Excelsior radiant fire with Merkit Maxitron G30-ZRHSO remote control. Remote stopped working. Renewed batteries in receiver and remote but will not operate fire. I am disabled with severe Arthritis and need the remote. Have been quoted over £100 for replacement which I think is extortionate ( I am a pensioner). The fire was only about £250. Have read online that it may be the code needs re-installing. Grateful for any help or advice. Shirley