I agree - you should let the store know that what they offer as a restroom is insufficient. I'm not sure of the laws - and if a store posts that they have no public restroom they can deny the public access to the one the employees use - but it's worth researching.

I rarely go anywhere that I don't know exactly where the restrooms are. And which stores have the cleanest ones (I detest public restrooms but sometimes we just don't have a choice).

Sorry you had such a rough time of it, B2Y.