Cannot End/Cancel my FNB Connect Contract

My FNB Connect contract has concluded at the end of July 2021 and FNB refuses to deduct the last debit amount of R121 to end the 24 month contract. I have tried contacting the bank and FNB connect, but they refuse to help. FNB refers me to FNB Connect and FNB Connect says that the bank does not allow them to deduct the final amount. By ending the contract and deducting the last payment, FNB would have to refund me an amount of R500 that I had to keep in my Savings Account for the entire period of the contract (24 months) in case a debit order was not honoured. All debit orders have been honoured on the first of each month for 23 Months!!! FNB refuses to conclude the contract just so that they can hold the R500 hostage!!! As long as they don't take the last R121 then I can't get my R500 back!!!