Don't know how to read mails

On 13 March I logged a request to have my banking details changed from fnb to ABSA. I received a mail the next day stating that 130318QNKLNP is my query number. On the 16th of March I received a mail stating that bonitas received a request to amend my banking details, amend being the magic word here. This was the last mail from them. The debit order still went of fnb so I assumed I must have missed a deadline. On the 9th of April I rep**** on the last mail I received asking for an update. The next day I received a mail stating that my query will be closed as my banking details have been changed to fnb. Not what I asked and how can they say it has been changed when it was fnb to start with. Today I phoned and after a rather painful conversation got told they cannot change my banking details without a bank statement. they never asked for a bank statement, they had a stamped proof of banking details letter. Why must I follow up after they closed the query and then they backtrack stating they don't have the correct documents. Pathetic if you ask me. All the info was in the initial mail I sent. Why not just reply to it and state that they need additional documentation, no they action the query wrong and then when they realize they made a mistake a month later, accuse me of being the reason for the mistake because I never sent them documents they never asked for.