@danievsg,
I am sure there are different rules for different States & Countries. I am a Property Manager, and Sales Agent for my business. Here, when you sign a lease for a specific period of time, you are locked into that lease until such time. However, once your lease runs out, you are expected to re-new or vacate depending on what the landlord agrees to. It appears that your (Agent) wanted the sale. But, was unable to be successful and so, the Landlord will lease again. And, it appears that the owner may have been told that you are difficult even though that is not the case and is taking the side of the Agent.
Why not ring the landlord again and explain what actually occured in a calm way and advise that you in-fact would like to remain at the premise for what ever period he/she agrees with.
Also, ensure the Property Manager is on your side because if you have to leave, you need a good reference. Ask for a print out from the Real Estate Company of rent payments made from their records as well.
Agents here have to give you (24hrs) notice for a viewing that is Private, or 1 weeks notice in writing for an open inspection. We have REISA (Real Estate Institute) here in SA, that can answer any questions you have pertaining to renting a premise and they have a website. See if there is a simular organisation over there for future reference.
I don't believe that you have to hand over a key, either. The Property Manager should have had a spare in any event. I believe that you may have the right, as is the case here, to refuse however, allow entry when you are at home, therefore the Agent having to make the time to suit you as you prefer to be at the premise.