I picked my dd up from holiday club this afternoon - the club is part of a local sports centre. They were all in a room upstairs which has windows across the length of the room. When I arrived 4-5 children were playing unsupervised on gym mats underneath the windows one of which had been slid wide open. One of the children was leaning against the window sill next to the open window in addition to the others jumping on the mats. The windows are not high, waist high i would guess and I reckon very easy for the children to fall out off. I immediately pointed this out to the two supervisors on the other side of the room, one of which said 'oh that shouldn't be open'. I reported the incident to the manager who was very apologetic. Since then I can't help thinking how dangerous the situation was and am really not happy. What should I do?