QuickSync for TikTok Shop

I originally had a good experience with this app as the agent I chatted with was friendly and helpful getting it set up but now it's become unusable.

The products simply will not sync to TikTok beyond the first 114 - despite leaving more than a day between uploads (TikTok has a 100 upload limit per day for new shops). The agents, although very polite, just go round in circles doing the same thing and not keeping me updated/not answering direct questions. They have "fetched" the products more than once and this had the side effect of un-syncing the first 114; this process takes hours each time. I've just tried to do it again and during the export, the system stopped and began to fetch the products all over again and this has again wiped out the initial 114 that it had synced. I've now reached the point of uninstalling the app and trying another as it's not working for my store.