IcelandAir review: Flight from Reykjavik to JFK

One of our suitcases did not arrive at JFK from our Sept 21, 2023 Icelandair flight #Fl613 from Reykjavik to JFK. I followed up with Icelandair (via email or phone) many times but the response was always that there was no status update or that they were still searching. This went on for 4-5 weeks during which time, I emailed a list of items in the lost bag, a description & brand of the bag, & any other requests they made. After about 5 weeks or so, I called to ask if they had concluded that the bag could not be located & the person who answered SEEMED to indicate that was the case. When I asked if Icelandair would then process the claim I filed, she said yes & would leave a note to have the person in charge of my case call me the next day, I didn't hear from her the next day or ever. I called again today & received the same response. The person I spoke with said she would leave a note with the same case employee. She also said there was no other phone # to call to complain, only via email, which didn't do any good, nor did the phone# I already called [protected], which also was useless. Suitcases can be lost, of course; HOWEVER, (1) how can Icelandair take more than 5 weeks to reach that conclusion; (2) how can Icelandair appear not to care & be so non-responsive when it was on an Icelandair flight that the bag was lost; & (3) why was I continually told I could only communicate via email or that same useless phone #?