<human>: I recently flew home from Barcelona and lucky me when I got to Montreal to go through customs my bag was nowhere to be found! They had me sign something saying that my bag was lost and that I didn't take it through customs but since I had a connecting flight that was all. Unfortunately that was four days ago and they still don't know where my bag is.  They just offered me $350 as compensation for the lost bag and its contents but everything lost was worth way more than that. I can see why they wouldn't trust my word on how much is lost but it was my backpacking bag, sleeping bag, clothes and about 5 weeks worth of souvenirs and such.

 Do any of you know how I should go about getting the airline to give me closer to what it's worth or if it is even possible?

Summarize the given text in a few sentences.
<bot>: Airline lost my bag and is offering me significantly less as compensation than it was worth. I don't know what to do next.