Lack of assistance

I have been requesting for my account number to be changed in order for FNB to Debit on my new account ,I was told to complete a form and email it to ********** .I emailed the form to the email address provided,when i called to follow up ,if my details have been updated and my form is received,I was told that they didn't receive my email however i received an automatic response that my form was received from FNB but the call centre consultant says that they didn't receive my email .How many times should I email the form, How many times should I go to the FNB branch to get assists. I have been going back and forth calling FNB going to the branch,but I fail to get assist from the FNB staff. The staff seem very clueless and unwilling to help.I am getting impatient and frustrated because i am not getting assist for a simple thing.FNB is said to be the best bank however it has failed me, dissappointed customer.