Rent gone into the sea?

I have been using this agency for almost 2years and havent had any issues until recently, manager is holding my rent back due to maintenance which needs to be done. I havent agreed to any of the maintenance, yet he doesnt want to release my funds. Rent for Aug, Sept and Nov are outstanding.

I am so tired of sending them mails and calling just to be ignored, Johan is dodging my calls and will not return any calls. They will also not respond to any mails

What must I do to get my own money which is due to me from this agency?