Unsatisfied customer with fnb

We have been with fnb for more than a year and have been playing lotto and powerball through the fnb app... On friday i got 4 numbers in which the devision said i wonR1069 but they only payed me R21. 70. I have been calling since Saturday to collect my winnings and they don't want to give my money that i won fair and square. Im very unsatisfied with fnb service on this matter and i want my money.