Can a plumber charge drive time and send 2 plumbers without prior consent?

If you did not get a quote or proposal for the work in advance, they can charge any amount that is "reasonable" and charge for more than one worker if, again, that is reasonable--your opinion as to how many men were required is not relevant. This is why it is important to get estimates before work is done, whenever possible.
You could refuse to pay, let them sue you, and try to prove in court that what they are charging is unreasonable. But to do so, you would need to get "expert testimony" from some knowledgeable local licensed plumber who also examined the work done, who can offer a meaningful opinion, based on training and experience, as to how much work was involved, whether it was a one- or two-person job, a reasonable hourly rate in the area, whether If you did not get a quote or proposal for the work in advance, they can charge any amount that is "reasonable" and charge for more than one worker if, again, that is reasonable--your opinion as to how many men were required is not relevant. This is why it is important to get estimates before work is done, whenever possible.
You could refuse to pay, let them sue you, and try to prove in court that what they are charging is unreasonable. But to do so, you would need to get "expert testimony" from some knowledgeable local licensed plumber who also examined the work done, who can offer a meaningful opinion, based on training and experience, as to how much work was involved, whether it was a one- or two-person job, a reasonable hourly rate in the area, whether plumbers local reasonably or regularlly charge drive time, etc. You would have to pay for this plumber's time (unless you have a friend or family member who is a local plumber who'd do this for free), so even if you were able to prove in court that a reasonable cost for this job would have been, say, $350, given that you'll be paying a plumber to testify, you could come out as bad or even worse off. There may be no good options to contest this; your best bet may be to try negotiate to an amount you are willing, even reluctantly, to pay.plumbers local reasonably or regularly charge drive time, etc. You would have to pay for this plumber's time (unless you have a friend or family member who is a local plumber who'd do this for free), so even if you were able to prove in court that a reasonable cost for this job would have been, say, $350, given that you'll be paying a plumber to testify, you could come out as bad or even worse off. There may be no good options to contest this; your best bet may be to try negotiate to an amount you are willing, even reluctantly, to pay.