There are two reasons your monthly bill might increase—your promotional pricing has expired, or if you didn't sign a contract, some companies are subject to increase their service by pennies. For example, when you get DIRECTV, you'll receive a promotional price for the first 12 months, and then your monthly price will increase in year two. It's definitely not good for your blood pressure, but if you're careful, it shouldn't come as a surprise. Make sure to ask about any price changes that may happen after your promotional period ends so that you're not blindsided with a giant bill.