Update:

I have just received a call from the FFP department and it is confirmed the site is currently down for the purchase of Elite tier miles and they can not confirm when it will be up and running again. They said they would organise a payment link manually.

Within a few minutes a link to make a one off payment for the remaining tier miles required to gain Platinum status was received and subsequently paid for, now just awaiting the status upgrade.

Just a heads up for anyone else getting to status expiry, you may need to reach out to FFP dept to do as I did.

Cheers all.