Shopify Marketplace Connect

I don't pretend to know anything much about coding, but all I know is we used this app for years, and while clunky, it at least worked. That stopped about a month ago when their integration with Ebay stopped working. Despite assurances SEVERAL times from support that fixes were imminent, or had been implemented and just needed time to re-sync, nothing was actually fixed. We finally had to find another app to use for this (and they're working fine, so it's clearly an issue on this app's part, despite them trying to say it was Ebay's fault)