We guarantee that all glasses will be made to the exact prescription and measurements provided. If not we will remake the lenses for no additional charge. Since the height of multifocal lenses are placed using best practice and not directly measured, we will allow for one remake, no charge, to remedy any issues related to location of multifocal. Any other problems can be addressed by calling our toll free number, 1-866-291-6900, and we will work with you to reach a solution.