Maayishh- you can/ sort of just go in and hand in the documents but they don't like it. You do need to sit down with them to look over what you have brought. A friend of mine went to 'just hand them in' and was told he would need a appointment but was given one for the next day. I don't know about Mitte but in Pankow all the offices that deal with the EB are in one section so I guess he just went there and spoke to someone passing. Or- you can send a letter or fax (I know) explaining your situation. Remember to include you email address and phone number. I couldn't get an appointment despite months of trying so I ended up writing. I got a phone call within a few days to offer me an appointment two days later. It helps that they are very kindly pushing Brits thro as a priority. Also- if you know the Sprechstunde you could go then. They are listed on the bottom of any letter you get from them or ask at the relative BA.