In Sweden I've seen quite a few businesses sprung up for that, collecting overpaid rent through a legal firm.

Completely agree that if it's a similarly straightforward process there will be businesses offering to litigate on the users' behalf and collect a fee, I'd be jumping on it if I only had to file a report and wait for the work to be done to collect a couple thousand €.

It definitely does for canceled/delayed flight tickets. Some years ago we had a flight that was canceled in the last minute by TAP and we missed one day from our trip. We got 600€ back from each ticket just by signing up to a website and sending the ticket receipts.