Steel inside burger

I bought 5 burgers at McDonald's vereeniging. When I ate my chicken burger I found steel and drove back to the branch. I asked for the manager and I explained and showed her my burger . She then said there is no way this could come from them. She showed off the burger to staff. I then asked her to bring it back since its such an issue, she then said no they'll keep the burger and make me a new one . I am irritated because she made it such an issue. My plan was to return the burger and show her how negligent her team is but after seeing her I realize I should have just called media