I would imagine the changing transactions are also applied to their exports (like .csv files), so I would perhaps check these and then you could certainly query if there’s a way of omitting these from the export.
However, I would guess that NatWest are likely to advise you to wait for Open Banking where this process should be more reliable. It’s definitely a work in progress.
The list from Open Banking doesn’t list NatWest as being one of the supported ones directly, but it’s likely they are included as part of the RBS Group:
https://openbanking.atlassian.net/wiki/spaces/DZ/pages/23461910/Which+ASPSPs+support+the+UK+Open+Banking+standards
Once everything has been finalised on our end, we will be supporting this (more info here).