Personally, I don't now why anyone would want to bother with a return on a defective part, when ordered off the internet. Such a PITA! Especially such a high wear, problematic part like a coil. You would be better off going to a LPS, and purchasing one with a lifetime warranty.
While I'm at it... a couple of suggestions. Keep a spare coil, and a 1/4" drive socket set in the trunk. Just in case. Or... buy a cheap $50 Actron scanner. Keep that in the trunk, and when the engine starts misfiring, use the scanner to determine which coil is going bad, and unplug that injector to keep from burning up your cats, (platinum not feline).

You'll set more codes by unplugging the injector, but they can be erased for free.
Lastly... If your vehicle has 70,000 or more miles on it, without coil issues, and you have a coil failure. Replace them all, because the rest are soon to follow. Then keep the still good ones as spares.
From my experience, BWD's are good, and have a lifetime warranty through your LPS.
---Mike---