In the past few years i've migrated hundreds of sites while i worked at a web hosting company. I am a Wordpress expert but i can migrate simple HTML/PHP or other CMS based sites too. Try me out and i won't fail you!
I can guarantee a downtime free migration and i will also help you pointing your domain to the new location. I am familiar with all of the popular web hosting panels (cPanel, WHM, Plesk, ISPConfig, ISPCP, etc.) but i can do this process without any panel access.