Sorry, Thunderbird is provided FREE to the world and we do have a good free help forum here. If you post your issue, we will try to assist. Thank you.

It is generally the apps you paid for or by subscription base like you pay yearly for for some antivirus clients that you may then get one on one support by phone, chat or email because you well paid for it.

Mozilla does have some subscription based products like Mozilla VPN, MDN Plus, Firefox Relay, Mozilla Monitor Plus that uses a direct ticket support system here because the users get this as part of paying for it.

Replies can take anywhere from minutes to hours or longer as you only waited fifteen minutes in /questions/1457329