The taps in our bathroom and cloakroom are all loose. I've tried and failed
to tighten them using a tap spanner but as they have plastic nuts they still
twist when turned On/OFF and I'm wary of damaging the threads.

Is their a knack to this, should I use some sealant or similar under the tap
to help? The house is only three years old and they've been like this since
the beginning, one of those jobs I've been meaning to try and solve once and
for all but never have enough 'tuits'!

TIA

Darren