After update Bookrev Product Review Plugin White Screen of Death

I just ran the latest update of the Product Review plugin, belong to this theme and immediately my website was gone, and I could no longer enter via WP-ADMIN either. With help of my tech advisor I managed to fix it temporarily, but I know what the problem is:
In functions.php this was mentioned: Call to undefined function cwppos() in <b>/home/thequeen/public_html/wp-content/themes/book-rev-lite/functions.php</b> on line <b>479

So, by entering in a little complicated way I managed to deactivate the Review Plugin and am currently without. Which, to be honest, isn’t fun, because I have over 130 (!!!) reviews on there, now all missing information.

So, I would love for you guys to fix this issue so I can keep using the Product Review Plugin. Otherwise I would love to hear a good alternative that makes sure that all the info I used (pre/con:grades) gets inserted too (I have a back-up file from a few days ago, so only would be missing just one article).

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