found a leak coming from under the heater vent just right of the steering wheel. anybody heard of this before?

 

Aye, sounds like windscreen seal.

Has the car been in a front ender? Or ever had a new windscreen for any reason?

Try taking it to a decent windscreen place, have them remove the trim and look, they will be able to see if the seal is suspect.

Mine was, but it had had a new screen, so got sorted free.