leave license termination penalty clausr

I wished to rent a 1rk starting from 10 july 2014. 30000 deposit money given to owner and july month advance rent of 9500 was given. While making the deal we verbally mutual agreed for 1 month notice on either parties. No lock in period was agreed upon at such time. Again on 20th july owner approached me with draft agreement but on the day itself i explained to him that my sale deed has been finalised so i will not be requiring his premises. And we mutually agreed not to go ahead with agreement which i did not signed. Per our mutual understanding i verbally offered to abide by 1 month notice period l from 20july itself and thus bear rent charges till 20 aug 2014 which comes around 3500 odd. On 6th august i handed over possession back to him and asked for refund after deducting my due rent. Later as per our developments and condition I offered for a one month rent as penalty which comes around 9500 and refund of 20000 is asked. Landlord is asking for a one month rent of 9500 and additional 10000 as penalty and offering me just 10000 rupees as refund from my deposit of 30000. I am seeking atleast 20k as refund from my deposit money. He is even showing me a clause in unsigned draft which reads as 6 month lock in period. We both are having good relation till now and seeking legal advice.