What is the benefit to rent through an agency? would they represent the owner in case anything is needed with the apartment/house or their only role is showing the property and having the contracts done and thats it?
Some landlords only rent through an agency because they don't want to be bothered having to show the apartment themselves. Others won't deal with an agent, period. Some then have the agency manage the rental for them. Others don't and you have to deal directly with the landlord.
Agents are expensive (to the renter) - figure a month's rent or sometimes even two. But to avoid the fees, you wind up having to call and deal with the landlord for each and every flat you want to see.