It'll require a 'phone call. Sounds like the form never made it, once you're outside of the process it seems its hard to get anyone to take ownership. I had IFE miles credit before I got home once; the on-plane form does usually work.
With a phone call you should get a clear response there and then, or you'll need to write to whoever they advise.
Happily with BAEC, in my experience once, the agent has said something will happen it does (although 7 days can stretch to 14 on occasion).