Another consumer experienced exactly the same thing and kept in contact with me.
After speaking to the BBC Watchdog TV program and then contacting the manufacturer, I finally got a response, however, that was after being ignored the first time. So I contacted them a second time, not in an aggressive fashion you understand but after all I nearly lost my yacht to a fire.
I can confirm that they now have sent me a free updated set worth £120.
Two things I can add to this.
One, don't accept stuff when it's doesn't pass the test and secondly, always disconnect lithium batteries when device is not in use.
When I say I had a close call, it could not really have been much closer.
Finally, many thanks to Workzone for doing the honourable thing.