Mozilla does not have the resources to have call centres to do one on one support for their main products like the Firefox web browser for desktop and mobile. Thunderbird is operated by the Mozilla Foundation's subsidiary MZLA Technologies Corporation. Thunderbird is an independent, community-driven project that is managed and overseen by the Thunderbird Council. It is generally the paid for apps or subscription based apps that may get more direct or one on one support by phone, chat, email or ticket because they well paid for it. Mozilla does have some subscription based products (like Mozilla VPN) that gets direct ticket support here. Short answer is No, there is no one on one support by phone, chat, email or ticket for the open source free to download and user Thunderbird email client. Also you should not post your phone#, full email or such on this public community support forum as search engines and other bots may find it.