I think I'm having a similar issue. Was your second issue on the return journey of the same booking as the first?

I flew GLA-LHR-PRG, and had no catering on the GLA-LHR sector (a voucher was provided, on this occasion) as well as service in general being quite poor. Raised a complaint, and received Avios a couple of days later. Then on the return PRG-LHR flight there was no catering again, and no voucher was issued to me. I raised another complaint (on the same booking ref) and received an email very quickly apologising... and offering nothing more. It's almost as if I received my allocation for the outbound sector, I can't get any more for the return. I've responded stating I don't believe this resolves the complaint but heard nothing more and this goes back a couple of weeks. I do realise that complaints are stacking up...