Renewing C Permit

I'm getting into a bit of a panic about renewing my C permit. If anyone can help with some info/advice that would be very helpful.

Here's the situation:

My and my three kids C Permits expire very soon, on 7th November. In the summer I asked around about how to renew them, and someone told me I'd get sent renewal forms a couple of weeks before they expire. That seemed pretty last-minute to me, but I believed the advice. As predicted, renewal forms for my children arrived at my house last week (I completed them and sent them back). No form arrived for myself however. I was travelling this week, so hoping to find it on my home return today, but nothing has arrived. I can't find any C Permit renewal form online, so I'm not sure how to proactively do it. I can't get through to the OPCM on the phone at all, even after many attempts. If you turn up in person to the OPCM without an appointment they won't let you in because of Covid. You can't make an appointment online, so I've no idea how anyone has an appointment. I live in Geneva. The address on my C Permit is correct.

I am therefore stuck with a rapidly expiring C Permit but no obvious way to do anything about it.

In short, what should I do, and what happens if my permit does expire?

Thanks for any help.

Relax just fill and send in form K as per the indications below:

https://www.ge.ch/renouveler-son-per...is-b-durable-c

Also don't worry about losing your immigration status, unlike with B/L permits the permission to stay with a C permit doesn't expire together wtih the card. The worst that can happen is a 1000 CHF fine for late renewal.

I had some similar issues last summer. I left a paper trail - e-mails, letters - to make sure that it was clear it wasn't due to dereliction on my part. In the end I managed to get through on the phone and renewed the card (it was only an issue because we had travel plans, otherwise it's no problem), but it was significantly more stress than any renewal beforehand.