Comcast xfinity Internet special offer not actually available , Internet

Wanted internet service and received a special offer in the mail addressed to "our neighbor at . . ." for Comcast xfinity internet $19.99 for 12 months.  Called the 855-542-8881 number on the letter only to be told that the offer did not apply to me because it was address specific and only applied to 'another unit in the building' but that I could get the same internet service for $35 a month.

So how can a special offer addressed to no particular unit in my building be deemed to not apply to my unit?  In every other way I met the criteria.  My suspicion is that they had no intention of honoring this offer.