The only time I've had something similar was with the South Lounge Spa. There were no treatments for hours, so I asked if anything was available at B and was offered something without question - perhaps I sounded convincing!

MrsNWI and I had a bite to eat in the F lounge, wandered over to B, had the treatments then wandered back again whilst we awaited our departure gate - which inevitably turned out to be a C gate ...