The best effect college counselors have is when they work with you from at least sometime during junior year. I agree, both that it’s just too late for them to make a difference, and that anyone taking you on at this stage is more interested in $$ than actually helping you.
What’s your gpa?
Also being realistic, 29 is not 2 points below the average for those schools. The middle 50 for ACT at Cornell is 32-35, for Columbia 33-35, and for Barnard it’s a little lower at 30-34. Those schools are all reaches. Do you have a good spread of matches and safeties on your list?