Cat - N
When I take my 11000 for service, the embroidery unit is not removable so they look at the embroidery function as well as the sewing functions. So, it never occurred to me not to take the embroidery unit with my 15000...in its protective case, of course. Although removable on my 15000, the embroidery unit is part of the machine 'as sold standard' and 'spec'd' by the manufacturer, and it seems to me that it should be included in the annual service.
If I took ONLY the embroidery unit...not the rest of the 15000, or if the embroidery unit was an 'option' purchased separately (I have seen at least one model from a different manufacurer where the embroidery unit was an optional accessory), I could easily understand making a separate service appointment and/or separate charge.
To be honest, I don't know if my dealer charges separately for the machine and the embroidery unit, but I understand the additional monetary issue, too, since your dealer charges additionally to service the embroidery unit.
If your embroidery unit is working fine, but the service cost is inconvenient for you at this time, it would certainly be your option to have it serviced now or wait for a more convenient time for you and your budget.