How to assign different role to new user according to product role

Hello everyone,

I am newbie to drupal . I am facing a problem in role assignment. I have created three different roles for my membership site.
after creating a product in ubercart i adds a role for that product in feature tab. so i have created three product with there different role. In autoassinrole i have checked all my three role(created by me).When user completes checkout..all three role assigned to that user..But i need assign role to that user according to product purchase.

Please help....