The program OP is talking about is independent of any hotel mileage award programs and earns miles at a rate of 2 miles / $ (before taxes). OP did you use the mileage credit request form at https://www.delta.com/contactus/comm...qmileagecredit

The partner in the form would be delta.com/hotels. I would make clear in the comments that you are requesting the 2 miles/$ as part of booking the hotel through delta.com/hotels. If you are still having issues, the delta.com web support line might be more clued in than the general contact us support team. Their telephone number is 1-888-750-3284.