I would speak directly to the manager and see what his response is like, if he is in any way dismissive about it then I would make a serious issue out of it with customer services.

I once sent food back at a HI because it had mayo on it (I always specifically request not to have any), the food came back about 5 minutes later and the mayo had just been wiped off! It's lucky I'm not allergic to it, but the hotel didn't know that, it's things like this which can very easily cause someone ill health so it is your duty to make sure the manager cares enough to do something about it.