KJ (8.12.20): Unpublished because similar information is under the question "I've applied to the IRD for a payment plan..."
If you contacted the IRD by phone or email, they will usually respond to you through your myIR login, either with a secure mail or by sending you an electronic letter. If you're unable to log into myIR please get in touch with our friendly Support team, with details of the payment plan you tried to organise and we can contact Inland Revenue on your behalf to see what's going on.