Uhaul Dean haske Would not allow me access to my storage unit for months although payments were current , property stolen Columbus Ohio

I was denied access to my storage unit for several months.  I had paid fees back in the Lally of 2014. I made several attempts to enter unit , but uhaul  did not remove their black lock from unit. Therefore I had no access. I went to uhaul office on five separate occasions and was told that they would let the then manager Tony know.  Finally in March of 2015 , AL an employee at the request oh the new manager got the key and let me in. At that point I discovered some of my property was missing.  I have been spoken to in very un professional manners and was told my the general manager to file insurance claim ando not call them any more. I am sure I am not alone  because I had a similar problem a few years earlier with property' being stolen please help.