I understand your frustration. This happened to me once when I could not afford it and I vowed and declared it would not happen again. It has not happened to me again. I just may be very lucky though.

I always do the following:

• I insist that only my list of tradespeople be employed. I will not pay any bills that are provided by tradespeople who are not on my approved list. I get the real estate person to initial this. This stops them getting any back handers etc. Incidentally if you suspect your real estate agent has done this contact their representative group (REIQ) is Qld's.
• I talk to all tradespeople about their costs and charges before I even invest in that area. I want to know what the call out fee's are and anything else. I find this is possible by investing in an area you know. You may have lived near the area in the past, went to school etc in that suburb, the list is endless. This does not mean that I invest where I live. I have never done this. Some areas just have a chronic shortage of tradespeople. More means competition is healthy. If you think businesses are colluding tell "Fair Trading" in your state.
• I have never allowed a real estate person to tell me "what you ought to do is……". I listen to them consider what they say, I think further on and then make my decision.
• I make an extremely detailed list of everything that I can see that needs to be changed, fixed, installed etc, before I make an offer.
• When I do purchase the first things I do are change all light bulbs, batteries in smoke alarms and I change all the washers in the taps myself. I have found that the call out fees for the little but essential things are the deadliest to my bottom line. Preempt everything as far as you are able.
• I interview all real estate agents in the area. Then I choose the one who listens to me. It's surprising how many people in this industry do not listen to others.
• All of the agents I've dealt with all have someone who is licensed by the state building authority to do any building repairs and maintenance. In Qld this means that tradesperson can change light bulbs, reseat taps and washers, fix a bit of plaster/plaint whatever. A householder can do this themselves but they cannot always attend to investments themselves. This way you have the legal backup of using a licensed tradesperson and in general these people do not have the overly exorbitant fees. They still have insurance.
• Stand up and speak to the person who authorized a bill to be sent to you. Ask them how they have arrived at that figure. If it is not a logical response and your getting nowhere with them don't engage with them. They can turn nasty. Move away and ever forward. Also ask your agent to talk to them if you are not confident. That is what you are paying them for. Let them know you are not a happy customer and that you want the situation remedied. You may also be able to contact their representative group or authority like BSA (Building Services Authority, in Qld) make a complaint that's why the industry has the regulations. If all else fails contact ACA or TT shake their cage by all means but don't engage with them personally.

Sure, get mad but don't waste time and money getting even. LEARN LEARN LEARN.
Sure, there's shonky dealers out there. Don't waste time on them. Keep pushing on. Keep working towards your goal and only worry about the people that are locked in your house with you at night. You know what you are doing so stick to it.

Last of all NEVER LOOSE YOUR COOL with morons.

Keep smiling and keep going. I can assure you there are very reputable and trustworthy trades people and real estate agents out there.

Regards
fliptoplid