car was fixed by bmw back in early Dec.
Combination of 2 issues:
1) Thermostat - stuck open so water would not get chance to heat up;
2) Matrix - clogged with "goo" due to previous owner using non bmw engine coolant;
1st the Thermostat was replaced and the hvac system began giving 50% heat - but it was very random, such as cold on your feet, hot on face, passenger side all hot except for windscreen vent etc.
went back to bmw to complain, explained I thought it was a partially clogged matrix, master tech said no chance, refused to leave unless he tried to clean matrix. when he finally did cos he knew there was no getting rid of me, he had some special adapter, attached it to the bulkhead pipes, blew in compressed air, and voila out the other end came lots of brown gunk. straight away when we tried the heating, it was roasting. I had to say it to the master tech....."I told you so".
downside is now it gets too hot and the missus is always fiddling the temp settings. plus I'm constantly using the knurled wheel cos my lenses dry out. Ha!