I need someone Experienced who can Update my Premium theme to latest version -- 3

Hi I have a site in WordPress. I need the website theme update a service. The problem is this site has a history of breaking down while updating. 3-4 developers failed to do it here and elsewhere. Best practice would be to copy and take backup of the FULL site somewhere safe, preferably in my hosting and then do the update. So if the site is broken and cannot be repaired, then the backup can be used. But in any case, I need the site back with all the Preset Features intact. That's the main thing. You can do the work in your Computer localhost before doing anything in the live server. Please let me know if you can do? You must accept the project before I share you login details and U MUST CREATE BACKUP of the SITE and DATABASE before working through Anydesk. YOUR BID PRICE IS FINAL. NO LATER CHANGE IS ALLOWED. LOWEST BIDDER WILL WIN THIS PROJECT.