chevrolux:
The tradie can charge whatever they want if you haven't got a quote.
It's irrelevant whether it's too expensive or not, you've had the work done, now pay the bill.
IANAL . My understanding is that if there has been no estimate or quote given, then the charge must be 'reasonable'. If someone thinks they have been overcharged, they can contact other tradies to find out what they would charge for that work. However, from what the OP has said, they had already agreed on the price, which would be a quote or estimate.
I would look at how much productive time the tradie spent on the job, and not on their mobile, and find out what their hourly rate is and do a rough calculation from there.