Currently spending a sunday morning messing with router trying to update it. Having begrudingly changed ip and password to default it seems the talktalk app is not for huawei routers (yeah RTFM me...
) so the only way to update according to tt appears to be to by doing factory reset and waiting.....
Other than not doing what i'm told - I assume a combination of tr068 and remote management have the device talk to tt servers to report stats which in turn push new firmware of required (quoted as 48 hour delay)
Fingers crossed this actually works although am sceptical now not being a tt customer (not to mention disliking tr069 and remote management full stop)