I'm being bul**** by Standard bank .

I have been a loyal customer of standard bank for atleast 2 decades..but suddenly I'm being harassed and bul**** daily by unending calls from debt collectors claiming to be representing std bank. I had a savings account with std bank since i was a student in 1999,i continued to still bank with them when i became employed in 2005. My savings account was upgraded to a cheque account sometime in 2014. I even had a home loan and vehicle finance with them of which was both successfully paid up and closed.later in 2017 i started having "unauthorised /********** debit orders" on my current account where my salary was paid. The debit orders started with 2 debits orders, 1 debiting on the 15th and the 2nd one on the 31st. I went to centurion lifestyle branch to go sort out the problem.the consultants assisted me to cancel/stop the debit orders but said they dont promise the "cancelled" debit orders wont go off again as most time they are then redebited using a different reference number. I asked so how do i permanently stop this from happening? I was informed it couldn't be permanently stopped or cancelled then but ill just have to always check my statement and go report if i notice there's still debiting. I was visiting the branch every week as the number of the ********** debit orders kept increasing in my account. I ended up having atleast 10 of those ********** debits going through twice in a month on my account. I was always at the branch trying to either cancel or reverse the debits but they just kept taking my money *******ly and the bank was unable to help me instead i was once told by a consultant to try contact the originators/companies that were debiting myself and tell them to stop the debit orders. I didnt even have any company name or contact details of those companies.neither did the companies even existed. After months of having my money debited by people i dont know i decided to abandon the account by switching to another bank.I cancelled my monthly salary that was deposited into std and moved it to my new bank together with the legit debit orders i had while banking with std bank. The ********** debits kept on debiting and reversals of the unpaid debits were done living the account in a negative balance as there were no more deposits made to cover for those debits and reversal charges. Fast forward 2020 i receive calls from people claiming to be representing standard bank and they are demanding a payment of 5000 debt i have with std bank. i asked what the 5000 was for i am told i have an account which has an overdraft with std bank and i need to pay it as it has been handed over. To my knowledge i never had any overdraft in that account i have with std bank, and im accused of not "closing" the account thats why the debt has been accumulating since i changed banks. So it took standard bank 2 years to notice that there is an "inactive/ unused account that's in arrears and they never bothered to contact me and try to find out why im not repaying my so called "overdraft".firstly i have no idea i had an overdraft on that account.secondly i dont owe standard bank any money instead they failed to assist me as their loyal customer of over 20years banking wit them. Now they harass me by sending people to call me daily and threaten me with legal action if i dont immediately pay an amont of R5000 debt from what they suddenly call an overdraft. The consultants even have the audacity to accuse me of ignoring calls and trying to avoid repaying my debt. I am being bul**** daily to pay a debt that happened because of the bank's inability to assist me in cancelling ********** debit orders and for deciding to stop banking with them because of the poor service i was receiving?