The deemed acceptance only kicks in if the Contractor notifies that the Project Manager has not made their own assessment within the timescale. If the Contractor fails to notify then the deemed acceptance never applies. If they remind after 16 weeks that the Project Manager has not responded, it will still be a further two weeks before the original quote would be deemed accepted.
If the Contractor has notified that the PM has not made the assessment I do not think you can unilaterally resort to 13.4, especially when it is quite late in the day to make such a statement. Otherwise this would always be a get out of jail free card for the Project Manager in every situation. The contract is all about transparency and timely information.
Time for both Parties to sit around a table and review this matter together and come up with some kind of agreement as to what the value of this event should be - rather than both sitting in different camps waiting for the other to make their move. Following the contract should not be a game for the other to take advantage of.
If I read the thread correctly, the date for deemed accepted would be 2 weeks after notice ITO 62.6 even if the Project Manager has replied in terms of 13.4 asking for further information. He is limited to those replies listed in 62.3, if he hasn’t done that, no reply was forthcoming and thus quote would be deemed accepted ITO 62.6 due o non reply not ITO 64.4 due to non assessment.