Tenant Problem!

Hi! I have a problem with my tenant (yes, its possible!) I leased a 4 BR , 2 bath apt last 2008 in April. During the course of last year , the Master bathroom developed seepage problems. The tenants said that they have a contractor, who they got to repair and I naturally paid for it. This happened once again and I compensated completly. I however trusted them blindly and did not go to check what work the contractor had done. However, recently, last week..the master bathroom sprung such a leak that the water seeped through the master BR floorboards. After being informed about it, I immediately, the next day sent a different contractor, who said that the problem probably was manifesting for a longer time. Anyway, the seepage was so bad that my wardrobes in Master BR had to be broken. My contractor is charging me 21k for this..and has quoted that he will take 10 days to fix. Due to the inconvenience caused I have offered my tenants a reduced rent for the month (50% off). However, they want to move out by April 1st week. According to the contract they are required to stay till June. They are asking me to waive the 2 month notice period and to return the 2 months deposit when they leave.

In the past there have been issues such as they said that their water heaters were not working..I then went to Town Gas the next day, selected the right heaters and sent a Town Gas repair man. When they cam to know that to install new heaters, the required bathroom wall will have to be scaffolded.. they called me and said the old heaters were actually working.

Anyway, I don't want to be the evil landlady and agree that the bathroom seepage has inconvienced them.. but it is just an unfortunate incident which I am trying to solve ASAP. I am trying to understand the tenants mindset..as to why they would move out rather than wait for 1 week more, by then the problem would be solved. From my side since I have to pay mortgage every month, I know with the current market, it may take me some time to find a tenant.

Would appreciate your viewpoint