Can anyone suggest another way, such as warning off the pest controller beforehand, or threatening the contract of the property services guy who organized him at the request of the committee. And if anyone has bothered with an pre-emptive legal approach such as an injunction would you recommend that?
The Queensland body corporate equivalent on an injunction is an interim order but that is unlikely to be approved (according to their fact sheet) due to the absence of serious, irreversible harm.
I would start a normal process now with an application to the AG’s office for a ruling that the committee members who approved the expenditure be ordered to refund the Body Corporate the whole amount of the cost of the pest control. You don’t have much chance of achieving it, but it might establish that they are doing the wrong thing.
Or you could go down the conciliation and dispute route and although you can skip conciliation if there is a matter of urgency, again I doubt if this applies.
Threatening the property services person or warning off the pest control person is crossing a line (marked “strata nutcase”) so I wouldn’t go there.
The best advice I can give is to write to the committee and the strata manager and tell them that if they go ahead with this, you will seek orders from Office of the Commissioner for Body Corporate and Community Management that they individually repay the Body Corporate since they are knowingly defrauding the owners for their own benefit. This is not a case of them making an error in good faith since they have been told that they are doing the wrong thing and have chosen to ignore the advice.