looking for room or flat

Hello, my name is Ensar, I am writing from İstanbul/Turkey.
ı am looking for a room or a flat. My budget is mentioned above which is max 450 euros(all bills included). Btw ı have to prove my accommodation to the consulate of Hungary. This means that ı need an accommodation letter to prove my staying. This letter must be given to me before 16.07.2019 on Tuesday.

Some general requirement is written down below. 

General Requirements:

1-) Accommodation must be in the city center or those Districts I, V, VI, VII, VIII, IX, XI, XXII or Budaörs, 

2-) I would want to know, ıf ı am renting any room or apartment(or flat). Would ı get a letter to prove my staying in Budapest? Because consulate of Hungary in İstanbul want to look this letter for visa application. Otherwise, they don't give any visa.,

3-) Rental must have a proper Internet connection. (Because of my education on it.). 

Thank you very much