I use Risk Free about 10 times a month. If I cancel within the day, the original credit card transaction never hits my statement. If I cancel the next day, the refund shows up online one day after the charge appears. Net, my experience is that the credit card refunds posts as quickly as the original credit card charge.

So ... something is wrong in your situation. Does Delta show the risk free refund was processed within the window? My guess is there is something wrong with the processing of the original risk free cancelation. I do these online and make sure the reservation disappears from my list of itineraries.

Good luck