Open Source Content Management

I have had a 24months lease which started on the 1st of March 2010 will be expiring on the 28th of February 2012. In the agreement, there is a section which talks about escalation quote
“The Lessee acknoledges that there will be a rental increase of 10% on the expiry or anniversary date of the initial agreement, which ever comes first."

Since the anniversary i have been paying the same amount from the initial agreement (without the 10%) and the Lessor didnt complain. 10 months down the line after telling him that i am not going to renew my lease with him, thats when he tells me i need to rectify the shortfall. Was this my fault that he didnt notify me of the increament in time? Am i not going to loose my deposit because of this. Is it legal for him not to give me back my deposit because of this?

Did you pay on an invoice that was supplied to you on a monthly basis?

we were just given banking details in which every month we could transfer the rent into. My bank statement/ his would save as proof of payment.