change of bank.

I gave Discovery Health the change to my bank details to which they comfirmed in an E mail on 3rd. October in spite of listing the bank as FN instead of FNB.The debit order was to be effected on the 1st. of every month.Today is the 12.nov and nothing has been done.I have phoned them 3 times so far and spoken to 3 seperate women.Their replies have been dismissive bordering on being impolite .I have also sendt an E mail.No reply.