Hello,
I can understand your frustration with the Zoo Med devise you show in your post. Its unfortunately a P.O.S. I figured it out the hard way too so no sweat.
Heres what you do. My recommendation is that you go to the local pet store and pick up one of these Zilla Temperature Controllers. This devise ran about $35 at the local pet store here.
However you could go to a near by hardware store and ask to pick up a lamp dimmer, such as this one found here Lamp Dimmer Switch. There are literally hundred of different dimmer switches for lamps so its simply a matter of picking the one you want. The one linked has a nice little night light, which I thought was cool!
In the end please save up to get the actual temperature control devise (thermostat) as it will save you a lot of trouble in the long haul.
Hope this helps! I'm sure others will be along shortly to throw in their opinions.