I'd reconsider letting it ride and push this with DL and/or DOT. Delta has a responsibility to manage their codeshare relationships and appropriately display what you are purchasing. The overwhelming percentage of consumers of DL codeshares are not on these boards and believe they are purchasing a seat in F, even if the seat in F on those flights isn't much to get excited about. DL needs to take the responsibility to seat you in the cabin they are selling you, or fix their tech issues.