Robertshaw makes most of the thermostats for N. American gas ranges.
Are you sure it's the thermostat that's hooped?
There is another device on older models with pilot lights called a thermo-coupler. This has a bulb that sticks into the pilot light. When it senses no heat, it shuts off the gas to the whole system.
Call a plumber of gas fitter to install the thing. Service guys are made to sell factory parts,and the factory parts are Robertshaw.
I am inclined to agree with foodpump about the possibility of the problem being the thermo-coupler. I have swapped out a few of those over the years after they went belly up. Pretty easy actually. Never have had to replace a thermostat.