Find the width at which the layout breaks (I'd recommend testing in various browsers/configurations) and change the media query to change to the accordion view at a slightly larger dimension
The plugin documentation gives instructions in how to override the CSS.
change these values in the media queries setup might work for you:
max-width 767px change to max-width: 1197px (×2 instances)
min-width 768px change to min-width 1198px (×1 instance)
As you are using custom fonts, the tabs are out of alignment with the content and are positioned too high, if you'd like a suggestion of how to fix that, please turn off the minify option in W3 Total Cache as it is impossible to troubleshoot with the CSS minified.