Sjaakie, I don't know who's your phone provider (KPN is terrible with their rates), but it isn't expensive to call Disney. You don't want to know how many times I called to get ADR's, change them etc. And my bills? About 1 maybe 2 euros per month for the 1 or more hours I was on the phone per month. (multikabel standaard tarief).
The mail you recieved is from the concierge desk, I think. If I remember correct you're staying concierge and one of the services they offer you is taking care of the ADR's, while staying concierge. If you read around a bit on the DIS, you'll find out that concierge will actually get ADR's people weren't able to get themselves. This might be something to think about if you're not one of those persons who wants to be in charge of the actual booking.
You can book for all the days during your stay at that first 180 days before day, unless you would be staying at 2 different resorts (which are 2 reservations). HOWEVER!! 6 months in advance, like you are now applying is more than 180 days. Remember, a year has 364 days. December has 31 days, as do january and march. Februari has 29 in 2009, but that would leave you with 182 days left instead of 180. Disney counts 180 days, so it might just be they'll tell you 'wait another couple of days, not 6 months but 180 days in advance'.
