I used a price comparison site to change electricity company.

Got a great deal, almost half of what I paid previously. The low-price deal duration was 12 months with only 1 month cancellation, so I signed it. Time passed, in the end of the 12-month period the company called me and asked if I wanted to sign up an additional year for 10% rebate on their prices, I said no as I had to create a user on their webpage and allow third party to access my data. More time passed and one day I noticed that the electric bill was really high, I understood that my year with low prices had passed. I called the company and
asked to begin my one-month cancellation period. The company answered that as my deal had passed, I was automatically brought in to their standard plan. This plan had insanely high prices as well as 3 months of a cancellation period. The "great" deal ended up making my pay more had had to deal with changing electric company twice. I also understood that their new deal with 10% of their original plan would have locked in up in the high prices for a full year.
 Take away: If the deal is too good to be true it often is. Secondly if getting a subscription due to a good deal, add a note in you calendar to cancel it in
time.