Originally Posted by SWISSBOBBY

There has always been an easy solution to this problem... Tag bags that are the correct size for the bins before boarding commences... you either do this at the gate before boarding starts or you pass a customer service point to get a "green" overhead bin tag.
Only "green" tagged luggage is allowed onboard. Therefore, it has to conform to rules.
Install a self-tag machine at the gates so those who have not complied can tag their own luggage for the hold.
If bags are not tagged, they do not travel!!!
Then consistency. No exceptions, and gate staff, while checking stuff correct group... passport... whatever... as we enter the boarding queues, direct those with excess hand baggage to sort it out rather than letting it through.

Staff who do not comply and do their jobs will have questions to answer.

I would have it sorted in less than 2 weeks