Can I back out of car lease due to difficult dealer?

I just leased a second vehicle with the same dealer yesterday. I am very happy with the car, and I got a great deal; however, I am upset about something. When I was signing the lease, the Finance Manager offered be a maintenance plan for $11 per month that covers all oil changes and maintenance. Based on the amount I drive, I think it would be worth it for me, but I didn't at the time. I called the Finance Manager today (my salesperson was out) and said I wanted to add the maintenance plan. He said he would have to redo the paperwork, and the cost would be $22 per month since the $11 promotion from Honda ended at the end of the month. To me, this is completely unacceptable not to honor what was disclosed to me, especially since he never explained that it would be my final decision. How can I go about getting them to honor the original offer? I am thinking about returning the car and canceling the lease if they want to play hardball. The lease on my old car is not up until November, so I definitely have leverage. Please help!

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