Customer service is normally quick to respond - make sure that their reply did not
end up in your spam folder.
Also check the material status page (linked from the top paragraph of the materials overview
in the "Create" menu) - some materials may be backlogged if e.g. a specific printer needed repairs
or simply is in unusually high demand. Advertised production times vary by material and are given
in business days. While the order is in production, there is no further update on the status page until
it is actually shipped. (You will get an email from UPS with the parcel tracking code, but no further message
from shapeways when it is shipped.)
The wait you mentioned sounds about right for plated steel (16 business days) or ceramics (13 days
plus possibly affected by current backlog). Also if you put several pieces in different materials all in
the same order, they will be shipped together, i.e. after the part with the longest production time is done.