Under Surveillance

I was hurrying along, running some errands at C Mall when I came across a peculiar notice. A very baffling and amusing notice. 

Next to a display of portable vacuum cleaners was a handwritten sign that read:
PROMISES UNDER CCTV SURVEILLANCE.

I thought, "My eyes... something is wrong with them. Isn't it supposed to be 'Premises' instead of 'Promises'? Maybe the handwriting made the 'e' look like an 'o'..." 

I went to take a closer look to examine what I had read.

Ah yes, I have learnt something new yet again. A Single Letter can change the entire meaning of the word and sentence. Yes. It was definitely "PROMISES UNDER CCTV SURVEILLANCE". 

Wow, we really have to be careful about making promises.