Well verbal contracts are binding too...so if the rehab committed themselves to offer an alternative to AA they will have too or your deal with them in invalid. You say your in duel treatment, maybe they can start a
DRA meeting there or be taken to one. A DRA member can object to the
spiritual stuff and still be within their rights as a DRA member to do so.
Above all I get your point that you don't want AA as a part of your treatment. And even DRA may be too closely related to AA for you, as DRA uses 12 steps. The DRA steps are different but not that different from AA's 12 steps. But then again as a DRA member you can choose whatever healing path you want to and not work the steps.
I hope you can come to some mutual understanding with the rehab and get the treatment you expected to get from them.