Is possible to rewrite the plugin from the child theme?

Hi, i modified the file class-wc-smart-cod-public.php in public folder, and i want this change to survive plugin updates. So, i created this folder in my child theme.
/(my-child-theme)/wc-smart-cod/public/ and i put my modified class-wc-smart-cod-public.php there, but it is not working.
Do you know what could be wrong? is wc-smart-cod overwriteable?

Thanks in advanced