On 2/2/2018, A4 received a letter dated 25/1/2018 (link to PDF below) from an NDIA official asking to meet with A4.
The meeting was held on 30/1/2018 (before A4 received the written request - it was organised by phone and email).
Note that the letter says the purpose of the meeting was "to discuss your [A4's] concerns".
This letter acknowledges A4 raised concerns in correspondence dated 5 November 2017 and 11 December 2017. This letter didn't mention A4's letter to the Minister and Assistant Minister of 24/12/2017. However, subsequent correspondence shows that the NDIA officers present did not prepare for the meeting; they did not discuss any of the concerns A4 raised.
After the meeting, NDIA officials did not acknowledge any of the concerns A4 raised either from those letters or from the meeting in their written "summary" of the meeting, see letter 22/2/2018.