This incident has been resolved. We apologise for any inconvenience this may have caused

Facebook has identified the issue which is causing the error when commenting on Facebook posts through their API, and that they are working on resolving it.

We will update you again as we learn more.

We are currently monitoring an issue with Facebook replies. Some of our customers have seen an error when replying to both Facebook ads and Facebook comments.

The error code states: The item you tried to reply to has been deleted from Facebook
https://developers.facebook.com/support/bugs/2686748158316940/

The replies seem to be posting to Facebook correctly, despite the error code. We will continue to monitor this issue closely.