I flew with KLM to Bonaire from London recently (via Amsterdam). On the way out my 26kg case was considered no problem. In conjunction with my girlfriend's 20kg case.
On the way back at Bonaire airport I was told that this was too heavy and that I would have to pay an excess charge.
I was given the option of paying 40 Euros as a Diving Equipment surcharge or paying for 4kg of extra weight if this was cheaper. Turns out 4kg of weight would cost 80 Euros so I had to pay the 40 Euros.
This left a sour taste in my mouth with respect to KLM particularly when flying to a destination where I am sure nearly 100% of its tourism is diving related.
Curiously my carry-on case was not a problem despite being over the 10kg maximum although they would not let me add anything to it.
This was an annoying situation given that the plane was only 1/2 full and last year I backpacked round the world with a 25kg backpack doing 10 or more flights with not one complaint about weight.
Mark