Re Qualifications, crewing advised (rightly or wrongly) that after I exceeded 90 days, it would need to be a TRE, and not a TRI to use the 120 day extension, however they couldn't find one.
From Commission Regulation (EU) No 1178/2011 (my underlining):
FCL.060 Recent experience
(a) [..]
(b) [..]
(c) Specific requirements for commercial air transport:
(1) In the case of commercial air transport, the 90-day period prescribed in subparagraphs (b)(1) and (2) above may be extended up to a maximum of 120 days, as long as the pilot undertakes line flying under the supervision of a type rating instructor or examiner.
(2) When the pilot does not comply with the requirement in (1), he/she shall complete a training flight in the aircraft or an FFS of the aircraft type to be used, which shall include at least the requirements described in (b)(1) and (2) before he/she can exercise his/her privileges.