I work for a UPS store, you need to contact the shipper and have them file a claim through the store that they shipped it from. Even if the seller is saying they shipped all included items and you are saying that you received different, the seller still needs to contact their UPS Store to file a claim. If the seller is giving you a hard time, I would contact the UPS Store that they shipped it from and explain the situation. To find what UPS Store it is, the label usually looks something like:

Seller's Name
UPS Store # ****
UPS Store's address

Basically the way insurance works is all UPS packages are automatically insured for $100. Let's say seller shipped it to you UPS Ground, no additional insurance, the item costs $500, and was damaged during shipment. Seller would file a claim with their store, the UPS Store would contact UPS corporate and send a claim request. Most time's with higher value packages, a UPS corporate employee will come out and inspect the item and packaging. If everything goes through like it should, the shipper gets a check from their UPS Store for $100 because there was no additional insurance included with the package.

I hope this helps some of yall out, if you have any more question's feel free to ask.