Deduction of Notice period from my landlord

Sir, I have taken a house for rent on 27/04/2014 in Bangalore. The rental agreement is for period of 1 year. Also it states that 1. I need to stay for minimum period of 6 months 2. Should give 2 months notice for vacating the house. As i was getting transfered to other place, I have informed my landlord about vacating the house on 08/09/2014 informing that i will stay till 07/10/2014. But as my tranfer got delayed, I informed my landlord that I will update them the date of vacating the house. I got tranfered in later date & i have mailed my landlord on 26/10/2014 that i am vacating the house on 27/10/2014. I have vacated the house & given the key to the owner. Now they have deducted 2 months rent & maintanence amount(For Nov'14 & Dec'14) saying that my notice for vacating the house got void as I havent updated them from 07/10/2014 till 25/10/2014. As per the agreement, I have stayed for 6 months as per minimum stay agreement & also given 50 days notice to vacate the house. Please suggest how to go about this issue. Regards Saravanan