Precise installation of sights near Stockton

I bought new sights for my g19 and I don’t trust myself to install them myself so took them to a shop to get them installed. First place I took it too, after waiting a week to take to the range, the front sight came loose. Took it to kw and they fixed it for me and they seemed fine when I took it to the range a week later. Now taking it out of my nightstand I notice the front sight a little off again. 8 years ago when I had new sights installed they NEVER moved once. I’m asking for a location in or near Stockton that will correctly install my sights that will last me years again?