Greetings Cards, Packaging and Sizing

I am having many issues with trying to list my greetings cards in FBA

- Firstly Amazon continually measure them incorrectly, which means I can't actually sell them as they would sell at a loss

- Secondly they appear to send them in an A4 envelope, which is not required as they are 15cm square and fit comfortably in a C5 (even in a cello)

- So, I was wondering what on earth everyone else selling greetings cards do? - Should I send without a cello wrap (to reduce size) - or will that just cause lots of damage and returns?

- Should I send them complete with the C5 envelope, which would increase FBA storage fees, but reduce the packing fee (presumably)

Any help gratefully received!