I don't quite get your post.
Were you travelling in ET/WT or CE/CW?

If the former you'd be entitled to one free piece - either the ski's or the boots but not both. If you also check in a case therekd be a charge for this. Or did you put your clothes in with your skis? If any piece was over 23kg there'd also be a heavy bag charge.

This policy has been in effect for 4-5 years now and is clearly outlined on ba.com. I'm not sure where you were incorrectly charged