Painting, rent stabilized apt?

My lease stipulates that I cannot alter my apartment in any way including painting and that the landlord is responsible for painting every three years. The latter has not happened in too many years for me to admit here! I have asked them to paint (over the past few years,) written a letter, and now am going to sent a certified letter asking them to paint w/in 45 days or I will have it painted and deduct from the rent over three months. Does anyone have any better suggestions? Should I just eat the cost of painting? Am I unrealistic in expecting them to do this? Thanks for any experiential advice.