Hi, if you have troubles with reaching a particular girl by phone, please observe the their availablity table (at least on this site, each girl should have one in their respective ad), which gives you a hint of their work schedule.
If you're not particularly picky, look for privates (=flats where these services are provided) with multiple girls assigned to the same telephone number - you almost certainly get a girl quickly (and at any day/nighttime). It's also easy to visually distinguish these ads, as their share a similar look/backdrop/style etc.
As for recommendations, it's difficult ti give because I (or anyone) don't know your preferences regarding age, appearance, services, techniques...use google translate and copy/paste to get some basic info.