Also might be time to learn to do that kinda stuff yourself, rather than relying on mechanics.

A radiator flush is really piss easy and only takes an hour every year.

Tools wise all you need is a hose, 10mm spanner/socket, 15mm spanner/socket and a 17mm spanner.

As you've said, being in sunny flooding Queensland means this is extra important.

Might even be worth replacing the temp sensor now that its 14 years old. The response to temp changes and quality of its readings degrades as it ages, which will have a bearing on fan control.