Difficulty booking S class fares

Hi all,
I'm trying to book the following itinerary with VS...:
Outbound: LHR-JFK-DEN
Return: SLC-LAS-LGW
With the VS legs as an S class fare for the extra TPs and miles for the fairly meagre price difference. However I spent probably a good 45 minutes on the phone with a (very nice) rep yesterday who seemed to have difficulty booking the S class fares. I've had this problem in the past where they don't seem to be able to find a compatible fare with the DL legs. Has anyone else had this problem before...?
After playing around with the booking system, the website automatically matches Virgin S fares with Delta L fares, though on her end this didn't seem to work. Very frustrating. She said she would investigate for me last night but haven't heard back yet. The other option she gave was booking them all as separate tickets which I'm not really too keen on.
I'm trying to book the following itinerary with VS...:
Outbound: LHR-JFK-DEN
Return: SLC-LAS-LGW
With the VS legs as an S class fare for the extra TPs and miles for the fairly meagre price difference. However I spent probably a good 45 minutes on the phone with a (very nice) rep yesterday who seemed to have difficulty booking the S class fares. I've had this problem in the past where they don't seem to be able to find a compatible fare with the DL legs. Has anyone else had this problem before...?
After playing around with the booking system, the website automatically matches Virgin S fares with Delta L fares, though on her end this didn't seem to work. Very frustrating. She said she would investigate for me last night but haven't heard back yet. The other option she gave was booking them all as separate tickets which I'm not really too keen on.