I'm most interested in what they said about point 1, i.e. that they did not 'hold' the data on compliance:
It sounds like they didn't even collect any data on what activity participants were being asked to do week by week, and whether they met those targets, at least not in an analysable format. To me it seems odd not to collect compliance data on such a key aspect of GET, particularly if successful therapy is to get participants up to 30 mins of exercise a day before increasing intensity further. If the aim of therapy is to reverse physical inactivity, surely they should have been measuring how much activity participants were actually achieving.
However, we know from the GET manuals that they did use planned activity worksheets (GET Plans and Progress sheets) and exercise diaries (Exercise Record), so this must have been recorded at least somewhere. I can only guess that if they say they did not hold it, that they did not hold this information in an anonymised format, or that it was never transferred to the main dataset.