I've had great experiences with CT customer service.
Once I got an order of 10 different 1/2 yard cuts, and one of them was the wrong fabric (just completely wrong- totally different line, different color). They sent the correct one out right away (thank goodness it was still in stock, because it was clearance) and told me to keep the extra.
This week, their thread went on sale, right after I just bought some. They adjusted the price for me with no hassle, and told me they can do it (just for store credit though) within 1 week of purchase.
My only somewhat bad experience was last black Friday- my order got repeated FIVE times. The woman on the phone canceled the extra orders (manually- they must have a new system now) but berated me for having pressed the button too many times. Their website was HORRIBLE that day, so I was VERY careful to have only pressed once. It was clearly their malfunction. I didn't appreciate the lecture, but at least it got fixed...