Broken Cart/Checkout after JQUERY version change - Organic Shop Theme

Hi. We updated JQuery and now the cart and checkout functionality on our site has broken. I think its because our theme (Organic Shop) doesn't work with the new version of JQuery.
I really just want someone to tell me how to go back to a version that will work with our theme.
We've given support access via the WPMU DEV plug in. Please help.