I Totally agree with Nai (well said hun)
and besides if it is their policy she was trying to adhere to, she could have said it better or atleast put it in an explanation like"I'm really sorry I wish I could but ....."
I also think it's disgusting you havn't received a reply to your letter yet, I would have thought they'd be quick to sort it out considering it IS discrimination!
If it were me, I'd be contacting my local paper, they'd be REALLY interested & maybe that would get the attention of the swimming pool place??? They'd be quick to respond with an appology then!

This treatment really irrits me, My sister has Prada Willi Syndrome and the way she was treated growing up was absolutely disgusting, I used to get so mad, & being so young myself, I never held back on letting people know! I think I used to really embarrass my mum sometimes lol!

I'm really sorry you & your little man had this happen, I really hope you get the appology you both deserve! & I hope they change their attitude quicksmart!