Bike shop problem

[ಠ_ಠ]

So, I bought a used bike from a local shop about two months ago.
I put down $50, at which point, they moved the bike into their rotation schedule while I finished paying it off. I noticed almost right away that the valve on the rear tube was crooked, but didn't get around to correcting that for about a 5-6 weeks. I took off the back wheel, removed the tire, adjusted the tube/valve, and put it back on.

I tightened the quick release levers as tight as they could go, but the tire was really wobbly. I throw it on a bus's bike rack and headed down to the shop. They said that the hub on the tire was loose (or needed adjusting, something), and sent one of their employees to the back with it. 10 minutes and $8 later, I had it back.

This past Saturday (2-3 weeks later), I notice another wobble - not as bad as the last, but definitely noticeable. I take it in, and they tell me first that the kid who did the initial repairs must have done them wrong, then told me that if it's hub damage, it couldn't have been their fault. they tightened it for me for free, and said that it'll be about $25 more for a permanent fix.

Something tells me that the hub was already damaged when I bought the bike, mainly because I've treated this bike like I do any other, and I've never had a problem like this with any other bike, especially after such a short time period. Is it possible the damage was already there? What would it take to cause such damage (READ: what did I potentially do to damage the hub)?

[GeorgeET]

What exactly will they fix for $25 to make the fix permanent?? That will point to what is damaged.

Crooked valve stem had nothing to do with it.

Hub can be damaged when riding it extensively loose, the bearings and races and cones will hammer themselves causing deformation and damage.

[ಠ_ಠ]

Fixing the crooked valve stem is what made me notice how wobbly it was, that's all. I know it didn't cause it.

[DaveM]

I'd guess it was either already damaged or not adjusted properly when you got it. It's also possible it was "fine" but something gave out after only a little riding. But there's probably no way to prove what happened either way. It comes down to what kind of warranty they offer and how willing they are to help you out.

If you open up the hub and can document wear that could only have happened over a long time period you might be able to argue it was already damaged when you got it. But it's a used bike. Again it comes down to what they guarantee.

My guess is your best option is to buy the parts they recommend but save a few bucks doing the work yourself.