DS has gone on a backpacking trip for 4 months in South America. Flew out on Sunday from Heathrow with two following flights. He was informed after second flight that his backpack was still in London and to get a code on arrival to trace. We had put one of those tracking devices in the bag. Nearly five days later it’s still saying it’s at Heathrow, the code just says missing luggage, neither airline or airport tell us what to do- all blaming it on each other. I’ve reached out via phone and social media. Has anyone got any advice that we might not have thought of? So annoying as it had meds/broken in walking boots/thermals etc that aren’t so easy to replace as normal clothes.