Can you not just phone the number you have (switchboard) and ask to be transferred - or is it the normal pre-recorded crap and press 20 different digits?
EDIT: I don't know what number you have, but this seems to be the main switchboard:
Sulgeneckstrasse 19
CH-3007 Bern, Switzerland
Tel: 031 357 70 11
from
here.
An then this:
Please call our visa information center at
0900-87-8472 (Monday to Friday from 8:30 to 17:30;
SFR 2.50/min), to make an appointment ....
.... but this states
non-immigrant visas.
from
here.
EDIT2: Here you go - this is probably what you're looking for:
Immigrant Visas:
Mailing Address:
Embassy of the United States
Immigrant Visa Unit
P.O.Box 3001 Bern
Phone: 031 357 70 11 -----
oops, ... same as above - so probably no way to shortcut the system.
General services by appointment only through phone or email
Closed on
American and Swiss holidays.
E-mail:
berniv@state.gov
from
here ... by clicking on "contacts us", top right of page.