i urge you guys help me with your adives

I need some help please
I have rented an accommodation as a part of a villa back in 2006 from a nice Indian man. At the time the accommodation included some cheap old wooden partition in the kitchen (only one sheet of wood with a door giving to the kitchen) which I didn’t like, so I told the Indian man to adjust it but he asked me to pay 300 riyals which I did but finally I did not like it as the kitchen become to dark and there was basically no air so I told him I will remove it and he agreed.
Later I did find out, that the Indian man was not the owner but he was renting the villa from a Palestinian man. A year later the Indian man and the Palestinian man did not get a long well and the Indian man decided to handover the villa to the Palestinian man. The Palestinian man made new lease agreement with me with higher rent and took from me 13 checks including one as a deposit.
I stayed 2 years in this accommodation and left it about a month ago. The landlord refused to give me the deposit check which he cashed on the first day I gave him the checks (I did react when I saw him cashing two months in a row but he said that it’s the same and that I shouldn’t worry since he gave me a receipt and he will give it back the day I leave the house). When I asked why he is not returning the check he said he has to spend this money for renovation which cost him 7000(then he said how much I could participate in this renovation cost) pretending I have given him the house without the wooden partition that I mentioned above that he has never seen but the Indian told him at the time and that some door locks were not working properly. For your information this guy never came to my place and never seen how it was inside and does not know that I paid for the partition and that the Indian agreed that I could remove it. Even when I used to cal him for maintenance issue he refuses and says that as per the contract the maintenance is on the charge of the tenant. Anyway he is so cheap.

Having said that, I feel so abused by this man who is a cheater and would appreciate it very much if you could help me with some directives and advices to get back my deposit. I am planning to go to the police but I would like to have as much as I could of advices.
Additional information on this guy: the villa is on a Qatari name because he is a foreigner and he can’t own a house in Qatar. The lease stipulates the Qatari name ho is is his sponsor or someone who helped him acquire or build this house but there is a mentioned with that the Palestinian man can sign for him. So the Qatari guy may even not be aware that this may is signing under his name. the check gave him are under the Palestinian man.