All agencies listing long-term rentals include hefty service fees and the money must usually be paid up front, as someone mentioned. If you can afford to spend this amount of money, there are other agencies which don't charge quite as much in fees and can provide better service than Paris Attitude does. I used PA when I first moved here, and did not have a good experience, but you always have to deal with the owner - rather than the listing agency - after you arrive. Since many owners live in other countries, it's really difficult to know how to choose.
If you Google "location appartement longue-duree", you should come up with other agencies. Most of them are furnished and well-maintained.
It's extremely difficult to try to rent an apartment in Paris if you are not working legally here, do not have a French bank account, do not pay taxes in France and cannot prove that you make 4 times the monthly rent. Priority will always be given to French students, couples and families with children.