Lufthansa has denied my EU261 claim in respect of LH2273 NCE-MUC on 31 July. (According to FR24 flight landed - not door open - 54 minutes late resulting in a missed connection to MAN leading to a >5 hr delay in arrival at final destination.)

The pilot made several announcements during the delay explaining the cause as being a baggage handling issue. The bag handlers had apparently loaded the wrong bag on the flight but they couldn't find it. They had to search through all the different containers so the delay kept extending by ten minutes each time. They then found a different extra bag. The pilot was himself very frustrated by the situation.

Depite several exchanges with Lufthansa's "customer relations" team, they are denying the request because "your flight got delayed due to Air Traffic Control".

My questions are:

1. What is the best source of data to support my claim (e.g. other departures from NCE on the same day, etc) or any other publicly available evidence? I have a silver subscription to FR24 if that is helpful.

2. What is my best next step - should I file a claim through https://soep-online.de/en/ or is there a better route? The flight originated in France, ended in UK, connected in Germany and I am currently resident in Austria - but I don't have sufficient language skills to pursue this other than in the English language (so if taking a small claims court route it would need to be in the UK courts.

Separately, I have to say the entire LH experience has been shocking, including the complete disregard at MUC for the missed connection (we might have made it if they'd opened the door more quickly, or provided assistance to connect). And the handling of our baggage also woeful - despite being rebooked onto a connection >5 hrs later the bags didn't make the connection and took a further 5 days to be repatriated, it was impossible to file a bag report online or by phone, communication was absolutely hopeless.