Surely the Strata Manager has some sort of professional (huh!) duty to properly record issues…. and they surely will have professional indemnity insurance. I suggest a scatter-gun approach – letters to Strata Manager, Conveyancer, Vendor and Vendor’s real estate agent alleging misleading and deceptive conduct, and indicating a preparedness to sue.
Work out what your claim is in monetary terms. Engage a solicitor to send another round of letters, then let the bargaining begin. If it’s not a huge amount the “professionals” (I use the term loosely, again) may decide to settle with you directly rather than damage their no-claim bonus on their professional indemnity insurance!