2009 BMW 328xi squealing noise

I went to jiffy lube for a simple oil change and literally 5 minutes after we left a terrible squealing sound started from the right side; it stops at higher speeds but eventually makes the car lag. We proceeded to go back to jiffy lube so they knew they messed up and she said “it could be from dripping oil on the serpentine belt” and after the manager looked at it they changed their story to it’s a transmission problem and probably someone else’s mistake from somewhere else we’ve taken it. thing is: we’ve never had any work done on it since purchasing the car, and the noise didn’t coincidentally start right after the oil change. after looking through a lot of videos of BMWs with similar whining, the closest to the noise i could find was one about the valve cover gasket and the valve cover. it sounded just like that squealing. So my question is, how can I get jiffy lube to own up to it, and what else could have happened to cause this noise RIGHT after the oil change?

Besides checking the fluid level in the transmission, what else does your receipt say they did to the transmission?

That right there says it all. We have heard this plenty of times before.

Does not sound like anything that would happen because of an oil change even one done badly. Knocking, ticking maybe some grinding, before I guess squealing.

How exactly does going back make them know “they messed up”

Never had any work done to a 10 year old BMW. Really. At least 9 years over do for that oil change. What other things have been deferred. Transmission service maybe.

You most likely can’t. And noises can in fact start right after work was done to the car and not be related to anything that was done.