If the Instagram account was disconnected, it might mean that the account password was changed recently. In this case, the account has to be linked again in the InstaFeed app. (How to link Instagram account to InstaFeed)
Ask the customer to unlink and relink the Instagram account. See if this resolved the issue.
Things to do if the above steps fail
1. Inform the customer that there seems to be an issue and that you need to engage the development team. Inform them that you will follow up over email once the issue has been resolved. Gracefully end the live chat.
2. Send an email to contact@zegsu.com with the issue description and the chat transcript.
The subject line should be: InstaFeed - Frequent Disconnection/Unlinking - <shop name>