Just had a thought. I think all the recent "bursting into flames" incidents have been with Lithium batteries and usually in laptops, whilst they are being charged. My Motorola phone used old technology NiMh batteries which are much less likely to give problems. Not to underestimate the risk with Lithium cells but if Chrissie's phone is fairly old it might also not be Lithium. Also the problem only happens whilst charging which, whilst dangerous to property, probably means your trousers are safe, Eric, unless you charge your phone in your pocket!
Tony