I asked my current boss about the company policy on this very type of customer support call recently - where you fixed the problem without replacing parts.
I pointed out that one of the metrics that my employer tracks is the 'utilization rate' - the proportion of the salaried time that is accounted for by on-site service, travel time, and phone support.
So I asked.."If I manage to solve the customer's problem over the phone in half an hour, it makes my utilization rate go down, which shows poorly on my performance stats. If I drive a few hours, perform some on-site service, and drive back, using up my whole day for the exact same issue, then it's great for my utilization rate, but it costs the company money, the customer is down for an extra day - but look at that utilization rate! So, what's the official policy, what do they prefer me to do? - As long as the customer's happy, we're happy," came the enlightened reply.
Ask your boss the same question.
Also, a big two thumbs up to all the people who emphasize "Listen to the user!", which often includes "observe the user", and "try to understand the user's thinking".
Bonus: one of my favourite sentences to pop out of the user is "See, I did it just like it says in the manual, and it doesn't work!". That's a trigger phrase for me, which causes me to reach for the manual, just so I can say: "Well, in the manual it says..."
Often, it's not really their fault, they're not used to reading technical docs.
And lastly: while I was on-site for another issue, the kindly older lady operator asked me, as she had heard that magnets could be bad for electronics, asked me whether the copper-magnetic bracelet she wore was safe to wear while operating the equipment.
I brought the bracelet near the CRT - you could just barely make out a ripple on the display. "Wow!," I ejaculated, "you'd think that at the price they sell these things, the magnets would be stronger."
I then took out my magnetized screwdriver and brought it to the same position on the CRT, showing her just how much it was affecting the display. I told her not to worry, it was safe to wear that bracelet, as her hands wouldn't be near the CRT anyway.
A month or two later, I was back on-site. I noticed she wasn't wearing the bracelet.