Unilateral changes made to Bond account

We have had our current bond account with ABSA for just over 10 years. We received a call from ABSA on 9 November 2017 advising us that they had made an error on our Bond and that we have not been paying enough. We asked for the original bond documents and a face to face meeting. On 27 November 2017 ABSA responded via e-mail and advised us that our bond documents were destroyed in a fire in 2009. We again asked for a face to face meeting to discuss the matter. On 29 November we received another e-mail informing us that our bond account has been referred to senior management and they would revert with a date for the meeting. On 18 December 2017 another e-mail was received indicating that a meeting would be scheduled. On 3 January 2018 we noticed that the required bond repayment on our account has increased by R4000. This was done without our permission and we were not informed by ABSA. We immediately sent an e-mail to ABSA asking that the status quo on our bond account remain until we have had a face to face meeting to discuss the matter. On 3 January 2018 ABSA responded that it was a mistake they had made in the first place and they can not revert to the status quo. Again promises were made for a meeting to take place. On 16 January 2018 we again e-mailed ABSA to request for the increased amount to be reversed. No response received. ABSA has admitted verbally and in writing that THEY had made a mistake. They have failed in their fiduciary duty to safeguard financial documents. They have made changes to our account without our permission which contravenes the National Credit Act. Now ABSA are simply no longer responding to e-mails, which forces us to take this matter public and warn all other ABSA account holders to check their accounts. And if you are a prospective ABSA client, please bear the above information in mind before making a choice.