They drop ship from various warehouses and what they charge for shipping is very reasonable compared to other websites. They can't control what the warehouse ends up doing.

They answer emails and I have even requested a call back and they called me within a few minutes. I have never had a problem with them.

That is the risk you take when you order aftermarket parts. I almost always order the part from the original manufacturer so I can avoid these issues.

Bosch and other parts databases claim the Crossfire uses two different oxygen sensors downstream and they are not different. Another example is they suggest different spark plugs for the Crossfire versus the SLK320 and that makes no sense either. Parts databases are not always accurate.

Even on Autohaus, the same parts aren't considered compatible for the Crossfire and SLK320 especially brake parts. That's just how it goes.