Sergant EC660-2 battery

I've been in contact with sergeant who said my tracker is not working due to stand-by battery malfunction. Seems a bit odd as the Tracker is normally powered from one of the main batteries. Anyway they sent me a replacement battery which is the wrong size, wrong voltage and wrong connector. The EC660-2 has an integral battery (picture) and as fr as I can see there is no replacement listed on the Sergant website, and of course, apart from a long message telling callers not to be abusive, they don't answer the phone. Does anyone know where I can get one of these ?
Thanks