I had a plumber come in to fix a leak near the water toby. I dug it up myself to save some money. The plumber came and fixed it in less than 35 minutes. However the bill charges 1.5 hours of labour. 

I never had the need for a plumber before so I don't quite understand why I am being charged for 1.5 hours (90 minutes) of labour when he finished the job in 35 minutes. It was during normal work hours as well. So no extra charges for after hours or something like that.

Everything else on the bill looks like expected, material costs, administration fee and vehicle charge. Is there something that I am not seeing here which makes the time add up to 90 minutes? I'd appreciate any advice you guys can give me.