Head Office Lack of Response is shocking

I lodged a complaint maybe 2 months ago , received a call from the manager of the branch which I had a fault with due to them giving me old food (zinger wings) and undercooked chicken. Her response was that she was sorry , my kid had an upset tummy the day after and all that was offered was an apology. The least that could have been done was a response from Head Office and a voucher for my money back to spend at a branch of my choice , why would you offer me a replacement meal at the very branch I complained about in the first place? I am really disappointed as we frequent this franchise often , I would have thought you regard your customers a bit higher than the response I received.