I do not understand how they can guarantee your admission into dental school. 3.33 is not a very competitive gpa with an 18 DAT. I am sure this is a misunderstanding because I am certain no school program can guarantee admissions into a dental program or else 95.639% of the people on here who are truly serious about dentistry would attempt it. Maybe you know some secret road no one else does.
I recommend looking at the pre-reqs required at the schools you want to apply. Go to a university and finish those courses (which may take more that 12 months). Try to get a 4.0 on them and study your butt off and get a 20+ on the DAT while gaining practical clinical experience along the way.
Basically, if this is what you want to do then work your butt off to achieve it.