UPS screw up

[seriously]

This may be the place to post this or maybe not-
We just got a package delivered from UPS. It's from my sister in law in New Jersey. I open it up there are several gifts and cards addressed to someone named Willa, Kathy, and Aaron. None of which live in my house. 8-D My first thought is the UPS store mixed up two of the packages SIL was sending out.
Well one of the cards wasn't sealed well so I opened it, it's signed Merry Christmas Love, Grandma and Grandpa and a crisp $100 bill falls out. Definitely not from my SIL! So the store mixed up her box and someone else's.
So what do you think the chances are that UPS will be able to straighten this out.
Poor grandma and grandpa.

[Mashara]

Sounds like a big oops. I don't know if I would contact your SIL or the UPS store first. She can yell at them a lot more, since she was the official customer. Good luck getting this fixed soon!

[ginger]

Call your SIL first to make sure she didn't mess up the labels. Maybe she was shipping for a friend too.

Then, she will have to call UPS to correct it.

[AAM2012]

I thought when you ship something the person sending the package puts the address on the box?

[MixedBerryJam]

UPS is advertising this season anyway (I've never noticed it before) that they'll pack your boxes for you, too. This sounds like a major screwup I can't imagine how they'll be able to resolve it satisfactorily. I guess they just collect on the insured value?