I had good luck in the past with carbon express. I'm glad to here thay replaced the shafts the first time. I don't know what more you can expect.
Do you stack arrow when you shoot? That could be the cause.

If you're truly unhappy I recommend Goldtip. I set up 4 of the dozen arrows I bought back in March. am still shooting those 4 and have better then 900-1000 shots on all 4 shafts and the still shoot as well as the day I set the up. They'll cost a bit more but I believe IMHO you'll never change after that!

Adams