What do you expect them to do? Pull out filament from their rears? No one forces you to buy bambulab filament. You do not have to buy their filament.
If.it.is.sold.out.go.buy.it.somewhere.else.
While 
supplies : last
Quite hostile thing you write.
@psinfie has a point. They made a marketing promise they don’t hold. It is not good customer service. They could at least prolong his membership by a month since he has no use of it at the moment.
btw. I have the same frustration. Just bought a printer, bambu promised a discount on the printer pdp on filaments which they don’t even have.