I was flying United and due to a 3 hour delayed flight I missed my connecting United flight to Mexico. So, United rebooked me for the next day on another airline (Areomexico). Our luggage didn't make it to Mexico. After spending countless hours on the phone with both Aeromexico and United (with both saying the other was responsible for finding our luggage) our luggage finally showed up at the airport in Mexico, 5 days after our arrival, and the day before we returned home. I have read that we should be able to get reimbursed for reasonable expenses (with receipts) for items we needed to buy due to our delayed luggage, but am not sure who to file with, Aeromexico or United. I fear both are just going to tell me it is the others responsibility. Any idea who is responsible for reimbursements related to the delay? I think it would be Aeromexcio if I had booked the second flight with them myself, but United rebooked us with them.
The treaty which governs this is the Montreal Convention.
Article 36 and chapter 5 seem to indicate that you can claim from either, though I’m a bit too tired at this time to sift through the legalese.
I would personally claim from United since they are the ones you contracted with.
Don’t forget to mention “article 19 of the Montreal Convention” in your claim. Note the limits on responsibility (about $1700 per passenger).
See also https://www.forbes.com/advisor/credit-cards/travel-rewards/montreal-convention-luggage/ which explains a lot of it in much more accessible language and gives quite a few important details.