I got a money order for a deposit for an apartment but i got denied, but the money order is franked?

The money order is stamped on the back. I got it at my work so i asked my manager if i can get my money back and she said the apartment complex has to write me a check cus they ran it through. But the apartment complex is saying that she cant, and it will take 30-50 days to get it all back. What can i do? Please help <3