ABSA Account abuse

I have an Absa cheque, savings and credit card accounts and have been with them for many years. I was retrenched 2 years ago, went to the bank to have my UIF forms completed and confirmed my unemployment status. I stopped all debit orders and Absa could see there was no longer a salary being deposited. I had an overdraft facility of R2,000. Absa incurred debt on my behalf to the amount of R11,000, for which they are holding me liable. I received a message to the effect that 'since I closed my account' my internet banking is canceled. I did not close the account. I cannot access my savings account, they even blocked my banking app! How can Absa make payments if there are no funds? How am I to access anything? Absa has caused a very stressful situation here and I will not be held liable for payment they made with funds I did NOT have available. I do hope there is some way I can take legal action against them!