Expiration of checque account??

My Cheque account with overdraft facility has been unavailable ( apparently expired ) since Friday without any prior warning or notification. After numerous calls to the Call Center as well as going to a branch to sort this out, I am still without any information on why the account has been blocked and are unable to use this account which is my primary bank account. I find this extremely unprofessional as well as disrespectful behaviour from a bank that I have been with for 20 years!!! How do you think this is acceptable? I have been sent from one department to the other without a clear answer on what the reasons are. I also find it extremely worrying that there are discrepancies on Absa's sytem - the one operator confirmed that the last transaction she could see on the system was on 31 March, although I still used my card on 14 April?? How is this possible!? I have lost all trust as well as respect for this bank who obviously have no responsibility towards their long standing clients. Utterly, utterly dissapointed and extremely frustrated!