over charged ?

my girlfriend got the timing belt replaced on her 2000 s80 it has 140,000 miles. they replced belt but also did the water pump and a tensioner. Wondering if the pump and tensioner were nessasary, they did the job in 4 hours.
thanks

Did they tell you up-front they were changing the pump, or did they just do it?

If your water pump was the original unit, it was prudent to change it. At your mileage, I would guess the original pump would go fairly soon, even if it looks good now.

On many cars, changing the belt duplicates much of the work to change the pump. So, if you are changing the belt already, it will not add much extra time to change the pump too, ao you would save a bit of money and break-down hassle in the future.

But, it would have been nice for the mechanic to explain this to you and give you the choice before going ahead.

it was the original pump and I am told that "while they were in there it was a good idea to chage it and save the labor cost if it goes next week. It seems logical to me at 140k miles. I am at a loss about the tensioner, not even sure what that is and the part cost $110.00

It may have been the tensioner/idler pully for the timing belt, or for the accessory belt.
When these go bad they often make a squeaking noise.
Again, it's reasonable to change it, given the mileage. Like the pump, they do not last forever and are easy to change when you are changing the belt.

But imo they should have informed you about the change before going ahead, and received your permission to do the extra work. In my province (Ontario) the relevant consumer protection law forces auto mechanics to call customers about extras like these before going ahead with the extra work. Mechanics cannot just add unexpected expenses to your bill without proir permission

If this is not the case in your state, next time, tell the mechanic not to do extra work unless he speaks to you first. :)