cant make thermostat function work on oil heater

[troubledconsumer]

Hello, im hoping someone more familiar with appliances can help me figure out the dilemma ive been having with portable oil heaters, you know the radiator type that is sold by different brands but are all basically the same design. they come with two knobs; thermostat and power level. 

when i turn it on with the thermostat all the way up and leave it till its at the temp i want, ill turn the thermostat knob back untill it clicks which according to the instructions is how you set it to maintain that temp. but it never does, it’ll keep clicking back on and heating the room way past that temp. so i end up turning the knob back till it clicks and it just keeps heating… and ive been through 3 of them so idk what it is.

any help on this is appreciated 

[troubledconsumer]

i think the thermostats just not worth a damn inside the hot case, might buy a plug in switched one.

Thanks alot for the help guys!