If the your site was working on the old server - and the host moved your site to a new server - and now you have an issue - then there is some setting on the new server that is different than was on the old server.
i.e. the wordpress, theme and plugin code did not change, therefore is is a setting on the server.
This is not a issue with more than a few sites (two that I am aware - you and the other user) so it is environmental (ie the server you are running on) - your host is going to blame the theme and plugin because they don't want to spend the time looking into the issue. If they can point to an issue with the theme, I'll be happy to investigate, but it works for me and all the sites on the different servers I have access to (westhoost.com, godaddy.com, registar.com to name a few)
I wish I could do more for you but this is beyond the theme support that I can offer for free (being an unpaid volunteer moderator). I hope you understand.