Lens Tuning

So...
I recently bought a Canon 50mm 1.4 USM to go on my T3i. I LOVE it, but at low apertures, autofocus puts the focus about 5-10 feet in front of my target (50 feet away), making the picture unusable about 40% of the time.
My question is, where do I go\send my camera off to get my camera\lenses adjusted?
Thanks in advance!
I recently bought a Canon 50mm 1.4 USM to go on my T3i. I LOVE it, but at low apertures, autofocus puts the focus about 5-10 feet in front of my target (50 feet away), making the picture unusable about 40% of the time.
My question is, where do I go\send my camera off to get my camera\lenses adjusted?
Thanks in advance!