Unless the letter has been delayed in the mail - always a possibility - the APO has run out of time.
But as I haven't received anything in writing within 28 days, they now appear to be in technical breach of the ADMINISTRATIVE DECISIONS (JUDICIAL REVIEW) ACT 1977 - SECT 13.
Even if they decided they didn't have to answer, they had to tell me so, and their reasons for saying that, in writing.
Well well. I wonder what the penalties are? Time to get legal advice. Again.