Bicycle Mechanics - BB wrong size?

I purchased a used redline conquest about 6 months ago. After a while my bottom bracket started clunking and wobbling on a ride. I took it to my favorite mechanic who informed me that it was toast and would need to be rebuilt or replaced. After he had it apart He told me that it was a really nice TNT titanium bottom bracket and that it would make the most sense to rebuild it. Ever since then it has been made a clicking sound when riding out of the saddle and seems to be just a little loose. I have taken it back twice to be re-tightened but it doesn't seem to be working. Today he put a little locktight on the threads and torqued it down pretty hard to no avail. He says that it's probably just not a well fitting BB and suggested that I replace it with a less expensive and more common unit. What's everybody think? Is there anything else I can try before I give up the fancy parts and go to something more conventional? BTW this bike will be my racer in the the coming cyclocross season so high performance is key.

I am guessing this BB is a square taper. I would just say give in and get a Shimano sealed unit and forget about it. The amount of weight you are saving with the TNT doesn't seem worth the pain in the ass you are experiancing with it not being dependable. I went through the same thing about 9 years ago when I build up a bike and threw in a World Class Ti bottom bracket. I roasted the thing in about a month, it would squeak like a freaking canary and was driving me to the brink of insanity. I just decided to say screw it and threw in an XTR bottom bracket I never had a single problem after that. The ultra light stuff is nice but it doesn't always work as well as it should. I personally would rather have to not worry about anything on my bike and have it weight a few more ounces than have the lightest, coolest parts and have to constantly deal with problems.