My Excelsior Combi Shuts Down when using Washing Machine?

My Excelsior (White Label Ariston, manufactured by Merloni) Combi Boiler keeps shutting itself down. The only pattern that I can see is that this happens when the washing machine is running. On reset the fume sensor LED flashes, which would indicate that there is a problem with fumes or I guess the fume sensor.

However the Merloni technical line very quickly, and without listening to all the symptoms, decided that it was because when the washing machine is on a rinse cycle "all combi boilers" would shutdown in the same way. The reason given is that "all combi boilers" only operate when no more than one additional tap/appliance is drawing cold water.

This seems plausable, however I haven't heard or read anything about this obvious downside to combi ownership.

Is this the case, and if so is there anything I can do to help the problem (other than making sure that nobody touches the cold water when the washing machine is running)?