Mariej

I have posted this once but not sure where it went. I have just found out that there is someone living in my studio flat in Paris without my permission. I signed a contract with a rental agency a few weeks ago but a week ago he phoned and said they had found someone for 2 years. This was too long for me as I go there from time to time. Also the rent was very low 530 euro inc bills. He told me he had already signed the contract with the girl. When I said it was too long for me we had an argument and we both cancelled the contract. I thought it was mutual as there had obviously been a misunderstanding, I was looking to let it for 6 months at a time. It looks like he has gone ahead anyway. I feel shocked that they put someone in there without telling me, I only found out by accident when a friend went to check it out. I spoke to the girl and she seems nice but I am worried about leaving my apt with this agency who don't respect my wishes. However, I need to rent it asap. What can I do? Is that a normal price? It's 16m2 in the 2nd arrondisement. He has already got quite angry on the phone when I said I didnt want to rent for 2 years and I don't really want to deal with him. I am quite shocked that this has happened.Any advice? Thanks in advance.