Stunt -

Use the link above for BMW direct but I might as well ask.
Where are you buying your stuff from.

I ask because any reputable OE Equivalent would have been something like Graf or Saleri.
ALL of them, including the OEM from BMW are REMAN units. The thermostat would have been a Behr.

I would not lump it all that non OEM is junk. I think where you are sourcing the parts may be the issue...