This isn't true.
You absolutely don't need new hoses in order to run R134a. I guess they're advising that because either a) they want to change the connectors, b) they've heard through the grapevine or are genuinely concerned about the different gas molecule sizes between R12/R134a leaking through the hoses. Either way, it's not necessary.
You also don't need to take the pump off and drain it. I guess they're advising the pump to be taken off and drained in order to pull out any of the old lubricating oil that might be in the system - but that would be sucked out by their A/C filler when it pulls a vacuum onto the system to recover any old gas and check for leaks! I think they probably just didn't like the idea of potentially contaminating their filler with any old gas.
Try somewhere else - you may have more luck with a specialist mobile a/c re-gas company. That's who I used for my R12 car.