Are we being unreasonable?

Hello, Asking for advice.

There’s been multiple water stains on our ceiling after neighbour had bathroom & kitchen floor re-done. We were told it was our fault because of our roof extension then suddenly it was because there’s no barrier from her floor to the ceiling & they agreed to patch them up. We got extra advise as were told two different things & were told just to wait until neighbour was back in property using new bathroom and kitchen & bathroom for few days to see if any new marks appear. The company are now really angry at us saying it makes no difference whether they’re in the property or not using the bathroom. Because they’ve sealed everything tested it etc.

We’ve said we understand & appreciate we’re not plumbers but that’s what we’ve been told to do! Is the advice given to us wrong?! They’re really mad at us & almost cornering us into accepting the stains are just a result of the work, which it may be but furious we’re wanting to wait until she’s in the property.

We don't understand why they said to her it was because of our extension roof and not the work, then said it was due to the work, they won't acknowledge it so we don't trust them at all.