Sigma lens repair?

I purchased a 17-35mm Sigma EX lens for my canon D10 appx 4 years ago. From the time I bought the lens it was never sharp and really horrible on the right side even stopped down. I really should have returned the lens but at the time I shelved it and would occasionally "retest" it thinking maybe I was too critical, and every time it still sucked. Anyway now several years later I decided that I did spend around $400 for the lens, its not usable, I wonder if sigma will do anything about it since it is far from in warranty. I contacted Sigma and explained the situation and they told me where to send it for "evaluation" and a repair estimate.
My question is pretty simple. Is Sigma pretty good about stepping forward and doing the right thing on bad lenses? I realize I should have returned it when I got it but, well I did'nt, my fault. Anyone have any good or bad experiences with Sigma on "lemon lenses"?
Canon usually has bent over backwards to help in such a problem, how does Sigma stack up.
Also if they say they can repair it and I have to pay, is it going to be sharp as one of the "good ones" that they produce?

Any comments or advice would be appreciated.

I have ony had good luck with Sigma and SIgma service.

I have a 10-20 in for service at Sigma NY right now. I purchased the lens used but it is not that old. They sent me an estimate of $200 to replace the HSM motor, clean and adjust the lens, and ship it back.
I would guess they aren't going to fix a discontinued lens for free.

I have a 70-200 Sigma Apo Ex F2.8 got it used the autofocus started to go back and forth and takes like 1 min to focus sometimes so I sent it into Gentec International so the repair is 150$ I get my lens back the autofocus still not fixed they took off my Hoya Pro Digi Uv and put it in a bag and it got smashed on the shipping back to me. So far ill probably never buy anything Sigma ever again, I called and they said they will take care of it LOL. I'm a super mellow person but I cant help being pissed on this one. So now im waiting for it to come back the second time hopefully its sorted out properly this time. Ill keep you guys posted.

So I got my lens back after almsot 2 months out very lame, lens works good. They sent me a uv replacement which is 72mm LOL supposed to be 77mm so now I have to call them again. I have to say Im not impressed with Gentec International so far I mean seriously how hard is it to get the filter size says 77mm on my backup one I sent which I put on the lens and the smashed one too. Does anyone think I should just talk to management on this one????? as this makes the company look bad as a representative of SIGMA. Has anyone had this much problems with any company that is this big to screw up and keep screwing up.

I have dealt with Sigma center in NY once. Very happy with the service..... Of course, I dropped off my lens there in person and waited about hour for them to recalibrate my Sigma 50.