Last straw

I hate this bank with everything in me, can't wait to move to discovery. App**** for a loan at wesbank, got it and now they're trying to send me the debit order mandate so that i can approve it and can't cause all of sudden , this stupid bank doesn't recognize my id number!!!! ...a bank that i've been banking with for years using the same id nr and account nr. Just tell me how is that possible?????Called *** and the consultant couldn't tell me how and why was my id nr changed and by who