Impossible change plan from "individual" to "duo" during the trial period

[#1]

I'd like to change from individual to duo but i get this error:

Error: Unable to change plans. You may not be eligible for this plan, you may not have a payment method on file, or the plan may already be associated with your account.

My trial period expires on 14th of august

My payment method is set and is ok

How to change plan ?
I have read the faq "1-Month Free Premium offer" and it seems it's possible to change plan but I can't

...sorry for google translator ... thank you
Daniele

[Vasil]

Hey there Daniele,

Thanks for reaching out! 🙂
You can change your plan but this will cancel your trial, effectively shortening its duration. 
If you still wish to switch to Premium Duo, you can try doing so via this link here.

Hope this helps! We're here for you in case there's anything else.