So the tech shows up expecting to install one DVR, and is supposed to install three without any notice and it's not fair that he didn't do it for free?
1) This throws off his schedule for the rest of the day, so his later customers get their appointments moved back because he is now spending more time then allocated for this customer
2) The tech may or may not have had the necessary equipment to install 3 DVR's, since this would require a SWM install or a multiswitch that was not on the original workorder
3) The tech now has to spend time on the phone getting the work order changed, which is where the $130 charge comes from (this is D*'s policy, not the tech's), so that he gets paid correctly and can actually activate all three of the customer's receivers.
This entire situation could have been avoided by the OP telling DirecTV that he had obtained two additional DVR's from Best Buy when he made his appointment. But since he apparantely failed to do so, let's all blame the tech and DirecTV.