False advertising by McDonalds

Very poor service from McDonald Midrand Restaurant#*** . I tried to purchase 2 x Mcflurry for R39.95 under offers using the App but it did not work . I requested assistance from the manager Olga who mentioned the App offers does work and she was not willing to assist further .False advertising .This was the first time I used the App and it might be the last time time . Please stay to avoid misery.