New online voluntary NIC payments system

Is it really meant to be the case that only those who are still paying CLASS 1 NIC or intending to ( via payroll) can use this service? It seems that anyone who has already retired a few years ago and is trying to securely pay to maximise their state pension cannot do so unless they answer the question that they are still intending to pay NIC ( which is arguably correct if you include class 3 as paying NIC). Surely it is these people that the service is largely aimed at, but because of this apparent glitch they are all told to contact the dreaded Future Pensions Service telephone number which seems virtually impossible to contact??

Hi,
If you have checked with DWP that paying voluntary NICs are in your best interest and will increase your UK state pension entitlement please use the following link:
Pay voluntary Class 3 National Insurance: Overview
This provides all options on how to make a payment.
Thank you.