What you are looking for may be called a pressure-temperature balance valve. Grohe is a good brand. I selected American Standard. Besides the many sites on the web, check any plumbing supply, Home Depot or especially an Expo center if you are in a big metro area. Home Depot has a catelog area that can help you find something suitable for your needs. My knowledge base is the residential stuff that I bought for my bath remodeling job but commercial stuff is similar.
I bought a separate single knob temperature control and three individual shutoff volume control valves, one for each of three users. The users include a standard shower, a hand shower and two body sprays. The two knob valve includes a temperature control and a volume control. I think that my temperature control has a maximum temperature adjustment selectable from about 35 to 50 degree C in 5 degree steps.
John