If you feel that the statutory manager is not servicing the strata scheme in the best interests of the owners, then you can apply to NCAT to have the terms of their appointment changed (for instance, to include all major expenses being subject to at least two quotes).
This would come under Section 237.7 (below). But gather all the evidence for this that you can before embarking on what could be a tough endeavour.
By the way, no strata manager, statutory or otherwise, can prevent an owner bringing a guest on to the property. If you want another tradie to give you a quote, have them accompanied by a resident.
And remember, there’s a reason that tradies say having a relationship with a statutory manager is a licence to print money.
Tou might also have a look at this thread …
(1) Order appointing or requiring the appointment of strata managing agent to exercise functions of owners corporation
The Tribunal may, on its own motion or on application, make an order appointing a person as a strata managing agent or requiring an owners corporation to appoint a person as a strata managing agent:
(a) to exercise all the functions of an owners corporation, or
(b) to exercise specified functions of an owners corporation, or
(c) to exercise all the functions other than specified functions of an owners corporation.(7) Revocation of certain appointments
An order may be revoked or varied on application and, unless sooner revoked, ceases to have effect at the expiration of the period after its making (not exceeding 2 years) that is specified in the order.