ÀPM bus and Shoprite does not want to rectify my ticket

The Shoprite cashier at Jabulani mall made a mistake on my bus ticket she booked the 20thMay 2019 instead of 20th June 2019 , the problem is that Shoprite manager does not want to rectify the mistake just because I have signed, the APM bus also does not want to help either, and I have booked for 14 people which cost me an amount of R2000