Delinking of account

We have been having a business account with Standard bank since 2013 and last year November we made and arrangement that for any changes to be made on the account there must be two signatures of the director and signatory. The bank delinked my bank card and when I inquire they tell me that it was delinked by the other director being Zach Motlhabane and they did not want to hear my side of the agreement that the agreement that was made said that two both the account holders must sign and they treated me like a ***** and they even confiscated my bank card. My questions are why didn't they call the other director before delinking the card and if it was not necessary why did we make the arrangement that for any changes to happen on the card there must be two signatures. If maybe he has deregistered the other member at CIPC how did he(Zach) manage it without the signature. I believe there has been a breach of trust and security here. Please assist us in resolving this. We even went to our banker at Sunnyside branch Mokgadi Malema who said there is nothing she can do for us we must go to Brits branch they are the one who delinked my card from Brits