Needs improvement

I recently purchased new glasses (Frank Ortmann, DOB 11/11/1948). This was the third set in 10 years, and while I was very happy with the first two sets, I cannot say the same for the present one. To be more specific: The associate helping me with the selection of a frame and writing up the order was great. Unfortunately, my experience when I picked up my new glasses was not good. I picked them up on 4/23 and the associate made a small adjustment. Turns out that the glasses were sliding down my nose, so I went back twice on Friday, 4/25 for more adjustments. They are still sliding, although not as much as before. I like my glasses to be a tight fit and would like to have them fitted and/or adjusted to meet my requirements. I am looking forward to your comments an/or suggestions. Thank you