Sprint cell phone service

In the process of renewing my contract with the above they dropped my call 5 times and took 2 hours – at the end when I threatened to leave they said I would receive 2 $75 rebates, and 15% off my service every month for 2 years. After complaining for each month I received 1 reduction and they said the other credits were mail in rebates (which was not stated during negotiations. So far no rebates, one $75 credit and no credits on the monthly bill now. I will be complaining to the attorney general of the state of Michigan also.