Mice- Pet Store Problems(?)

[Crochet Hearts]

Hello all. smile
I'd like to know if anyone can help me answer a question.

The pet store in town, where I bought my mice: Ziggy and Luna, is a bit odd in my eyes. I visited a couple of months ago and found that they'd placed a baby/young albino rat in one of two mouse cages with the mice because they ran out of room for hamsters.
I did some reading before buying my mice so I think, hopefully I'm wrong, rats are natural predators to mice(had an old-ish book, it advised not even having a rat in the same room). I visited a month later and the rat was no longer in the mouse cage and had one of it's own. I noted something else was wrong then: I'd seen inbred mice before, I think, and it seemed they had a few in their cage(Usually they're hunch-backed, smaller than other's their age, and sometimes walk kind of funny). They do use fancy mice for snake food, but I still don't like it.

Is it needed for me to contact anyone about this, and who should I contact?  

[the naked pixie]

just keep a eye on them and if they continue to do things like this, you should consider contacting a local thing. for me its the rspca ( being in the uk)