Transportex version 1.8.2 Update to 1.8.5.

Hello Everyone,
My site was rebuilt about 2 years ago the website builder used Transportex theme and now there is a newer version available, I have tried to update my site to 1.8.5 version everything overlapped on both the desktop and mobile versions. Can anyone please help me? I’m just a plumber and don’t know how to do this as I am no longer in contact with the original website builder.

The page I need help with: [log in to see the link]