Rabbit Woes

I bought a rabbit from pets at home last year. I have had nothing but health problems the entire time; behavior problems such as fur-plucking -- something he's done since I bought him -- skin issues, digestive troubles. . . Now, recently, he's obtained mites from Pets at Home own-brand "dust extracted" hay (as said by my vet). Now I'm buying hay from a smaller pet store further in town as I just don't trust Pets at a Home supplies anymore.

Why are their animals -- judging from other reviews -- sick? And, more importantly, where are they getting their hay from?

When I bought my rabbit , they never once asked me for ID -- I'm in my early twenties, but can't so much as look at alcohol before being asked for Proof of Age at Tesco -- to check if I was old enough to purchase an animal. They told me he was a Lionhead and wouldn't be much bigger than the size he was -- wrong. (He is huge now, about the size of a small dog.) When I bought him home all he did was eat and drink for the entire day -- he was grossly underweight and dehydrated. And, shortly after his arrival, the problems started.

P.s No, I don't want to take him back because a) I've seen first-hand what the store manager is like when a customer dares to complain about the health and lividity of his pets - refuses to take responsibility, talks to them like a piece of chewing gum on the bottom of his shoe, and suggests that the customers may be the ones to blame by not looking after their animals correctly; b) sending him back to the place he obtained all theses issues in the first place would most certainly be the death of him -- the staff, clearly, do not know how to look after animals.