1) Stop being a drama queen
. The slot has been allocated. Shouting is rude.
2) No. You would merely put the date back as (at best) you would go to the back of the queue for engineer time. At worst, cancelling would release the slot and you couldn't be sure you would get it again. So you could cause what is worrying you to happen.
3) If you mean you have an extension socket as well as a master socket, it depends how the extension is wired. If you remove the bottom front plate of the master socket, (assuming there is a split across the faceplate with a screw each side in the bottom part), does the extension stop working? Be careful how you remove it as there may be wires attached to the back of the bit you are removing
The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
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