A promo rate is just that. A rate to attract customers. Beware that most promos come with a contract. Your more than welcome to change your provider once your contract has expired. But in the long run, bundled services are where your savings are. Also a company is willing to offer more freebies to someone who is getting all the products they offer vs someone who is just getting basic service. Also take into concideration that each time you change providers you have to have something done to the overall wiring scheme of your house. Over time, your house wiring can get all messed up, esp if the tech is overbooked, under trained, or under paid. This can cost you more in the long run.
A friend of mine, after the promo period called to see if she could get on another promo was told by the csr "You have to pay full price at some time"