I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked
the "increased emissions" warning light means nothing specific - there are close to 200 reasons this light can come on, most of the benign.
this could be anything from a simple sensor or loose gas cap to catastrophic engine failure.
you have asked for advice, and given what informationo I have, my advice is this:
I would strongly advise you have a proper scan and testing carried out by a reputable BMW garage - it souds like the current garage is guessing with your money and no familiarity with this vehicle.
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.