Worms at Nandos N1 City

Did a online for salad and quarter chicken, found a worm in my salad, I immediately phoned them where the manager only came and said sorry and offered me another salad I was sick for the rest of the day and yet they offered another salad, I was contacted every now and then and then they still had thee audacity to tell me their area manager wants this matter resolved so I can either take food for the same amount or get a refund asap. I'm so disgusted with Nandos N1 City. Not even sure if I ate a worm I could have been hospitalized due to their lack of cleaning their salds properly n yet they feel they don't owe me anything. I'm not letting them of the hook.