Directv directv Internet

I signed up for a 2 year contract with directv in January of 2011. The agreement was that the 2nd year my monthly price would got up by $20 per month. They did not make any mistakes in the first year of billing. Starting in January of 2012 my bill is $50 more per month. When I called, they said that I have $50 in credits that expired, not  $20 which is what I was told. So now I have to pay $30 more per month than what I was told I would pay. I have had similar experiences with At&t. The problem is that the reps get bonuses and / or commissions. I am sure most of those reps do not lie, but a handful will lie to make more money. If they get caught, what's the worst that can happen? They get fired? But why would directv fire someone who is generating income for them, so the managers just look the other way or may be give them a warning. The system is wrong, and they know it, but they have no incentive to fix it. Every once in a while they will settle with a customer, but in the long run they make more money by allowing the misrepresentations to happen.