If you want a hot black girl I'd agree with Matri13 and head straight to Mary at
OzA 13 (click the link for a photo of the location- it's the middle door of that building, with the red-coloured windows above, marked 13-M) on nightshift, starting roughly around 10pm and working 6 nights per week except Mondays I believe.
Mary has recently increased her prices to €50 for CBJ only or €100 for suck & fuck (like a lot of OzA girls) but she's pretty good and very hot! She says she might stop working in November so grab the opportunity while you can.......