I have a 14.1hh Welsh sec. D (welsh cob) and i find it so hard to feed her and get the right balance!
She was on Allen&Page fast fibre but didn't east it so i moved her back to HiFi Lite and Pony Nuts and now shes getting to fat.
What do i feed!?
I also feed her garlic and equivite :)x
I would approach them in a calm manner and show them what for, in polite terms. It's unfair on you to do something like that, explain to them how dissapointed and appauled you were. Good Luck! :)