Mistake that was done

I'm having a problem with the Shoprite at Jabulani mall , I bought 14 tickets frm Durban to JHB which cost an amount of R2000, now the cashier at Shoprite Jabulani mall made a mistake by printing a wrong date the 20thMay 2019 instead of 20th June 2019 , the manager at Shoprite Mis Johanna is put a blame on me that I have signed as if everything its correct plz help me , I just want them to change the date back to 20June2019