My neighbor changes his own oil in his 2000 V6 Accord, except in the winter, when he has it done by a local independent garage. The garage mechanic apparently reinstalled the oil drain plug using an impact wrench. So when my friend tried to remove it using a 17mm socket, it wouldn't budge and he rounded off the head of the bolt to the point that now he can't grab it with anything. Is there any easy way to get it out? He doesn't even want to deal with the garage that caused the problem, he's through with them, cause he specifically told the guy not to overtighten the plug. What should it cost to have a reliable garage fix this?