It seems that if you are in a big market like NY they don't allow these types of free "upgrades."
I tried swapping my old model DVR for the new 7232 model and they said that they don't have any in stock. A few months ago all stores in the NY Metro area, when called, claimed that these DVRs are available only via online odering, i.e. paying a fee.
I guess if there is too much of a demand for a free upgrade they will ration the supply to cut costs.