I was not able to find a lot of information on the company listed in their terms of service (MJH BRANDS INC dba BuyTrustVolt) and the website was just registered a couple of months ago. Those two things alone would make me cautious.
However the TrustVolt product I am looking at says it filters electro-pollution, and does not claim to lower your electricity consumption. The most effective way to lower your bill is to cut your usage.
Some providers offer home energy monitors, which you can use to see in real-time how turning on and off certain appliances can affect your usage. This is a great way to take control over your power usage and find ways to make it more efficient.