Request to change banking details and debit new bank account

I sent several e-mails to Hollard requesting that they amend my banking details and debit new bank account. I am aware that they do read my e-mails, because I receive read message but they do not come back to me. I now receive sms's that my funeral cover will be cancelled if I do not pay. I even asked them to forward me their banking details where I can deposit the money. I haven't received any response.