PhotoDay works with some of the finest volume photography labs in the country. If at any point you'd like to use a different lab from the one you initially chose during the signup process, you can add further labs to your account.
To do so, go to your My Studio section in your Settings. The settings link can be found in top right area of the navigation bar.
Then, select Labs from the menu on the left. You will then be able to add any other lab you might wish to your account by selecting the Add button under each lab icon.
Now, when you create a new price sheet, you will be able to select which lab you want to use.
It's as simple as that! You can add as many labs as you like to your account, though the initial lab with which you signed up will by default appear at the top of your lab selection menu.