sherwin will access your situation and assist you. They are great about this.
There are many reasons for paint to peel off and although lack of priming could be the cause, I do really doubt it. The only reason that I could be wrong is if the painter was painting over bare never before painted wood. I only use a primer in my business when there is bare wood or where I have sanded down to bare wood and then use it there.
I will give you a list of other main reasons for paint to peel:
1) unclean or chalky surfaces
2) applying paint in direct sunlight on hot days.
3) applying paint when the temp is below 55 degrees that night.
4) applying paint when the surface is too hot.
5) USING CHEAP HOME CENTER PAINTS. especially Behr.
If you are painting a surface and before that you can run your hand over the surface and your hand comes off chalky then that has to come off first.
Duration, you know, I have never understood those years of durability that paint dealers and companies come up with. My favorite exterior paint is Sherwin Super Paint and A-100 paint. One has a 25 year deal and the other has a 15 year. Regardless of the paint you use, your home needs re painting every 7 to 9 years regardless of that year that is printed on the paint. So my point is why spend almost $50 a gallon for Duration when I guarantee you will need re painting in 7 to 9 years. I know all about Duration and the special resins and special platelets that do all that bonding, but I promise you you can get just as good paint from Sherwin at half that price and more coverage also per gallon.
If your paint dealer is honest with you, he/she will tell you that Duration is not selling and people do not want to shell out that much money for a gallon of paint.
Off my soap box.
I personally in my business only use Sherwin Williams Paint and Benjamin Moore paint.