4-door E46s frequently have window regulator failures. You can find the part cheaper (actual BMW item or aftermarket) - in fact, FCPEuro.com is having a sale this weekend (up to 15% off on some parts) and they have a lifetime replacement guarantee, so it will be the last one you'll pay for - if your mechanic will let you provide your own part.
You need to remove the door panel & vapor barrier to confirm that the regulator is the issue, but you wouldn't be the first one. Good luck!
Last edited by John in VA; 08-30-2018 at 04:52 PM.
2006 330ci ZHP - Silbergrau Metallic / Stoff Laser/Anthrazit / Alu Black Cube trim / Adaptive Xenon headlights / HK hi-fi system / heated front seats