Voltz came highly recommended by friends of ours so we decided to give them a try. We asked for their help with three issues:
(1) I had a bathroom light that stopped working. Last time this happened it was the G24q 18W CFL bulbs being broken, and replacing them with new bulbs worked, so this time because of being green I purchased LED bulbs, and they would flicker a bit and stop working.
(2) We had a set of LED lights that would flicker badly when dimmed and occasionally still flicker when the dimmer was turned up all the way.
(3) We had some general flickering problems with all lights in the house, especially when major appliances would turn on.
Voltz had a very good attitude and service in trying to address these issues:
For (1), initially they pointed out that the LED bulbs I had purchased were 9W instead of 19W. When I pointed out that the listing said that the 9W LED bulb claimed to be a 18W CFL equivalent, they said that perhaps the ballast on the fixture wasn't rated for LED and they read out a model number for me to call the manufacturer. One phone call to the manufacturer later confirmed that the manufacturer didn't have an LED retrofit, and so they couldn't guarantee that an LED would work. So that was all Voltz could do and so they left the task unfinished, but now I knew to return the LEDs and order replacement CFLs.
For (2), Voltz said that the reason was the dimmer switch not being able to handle LEDs. They replaced the old switch with an electronic low-voltage dimmer switch they had, which cost me an extra $100. After replacing the switch, the flickering wasn't as bad, but still noticable.
For (3), they asked if we had had any major changes that caused it. We had a new HVAC installed over the winter, and the AC unit started running heavily because of summer heat around the same time the dimming happened. So Voltz said that was probably the cause, and that there wasn't anything they could do about it.
They replaced a few bulbs (since they had their high ladder), and we were reasonably satisfied at the time, even though none of our problems had been fully fixed.
A week later, the bulbs arrived. Replacing them, surprisingly, only worked for a day -- then they stopped working again. Since Voltz had been unwilling to open up the light fixture last time, I figured it couldn't hurt to try another electrician.
The other electrician did some things differently:
(1) The replacement CFL bulb worked again after they shut off all power (see (3) below) and turned it on again. They suspected a failing ballast, just like Voltz. The difference here is that the other electrician had some experience with these fans and suggested that they'd be willing to help install a replacement if it became necessary. They also tested out my old CFL bulbs and confirmed that the bulbs weren't the problem.
(2) They noticed two things that Voltz didn't -- one thing is that the LED bulbs we had installed weren't dimmable. The second thing is even with dimmable LED bulbs, it wouldn't work -- Voltz installed a electronic low-voltage dimmer, when what we needed was actually a LED-specific dimmer. The other electrician then replaced the dimmer that Voltz had installed.
(3) They approached this problem by first suspecting that there was a possibility we had a loose circuit breaker. They inspected this by shutting down our power and inspecting the tightness of all the circuit breakers, at both main power and two sub-panels, something that Voltz didn't suggest. While they didn't find anything, they did make one recommendation that Voltz also didn't suggest -- that I call the power company (PG&E) to have them inspect the power on the outside of the house to see if there were any potential issues there.
So I send PG&E a message, and next day they came over to inspect the outside of the house. This is where the surprise happened. Within minutes, PG&E discovered that the neutral power cord to our house was severed, possibly because of tree growth or squirrels in our backyard. This is called a broken neutral, and if you look on line you can see that it's very risky. So risky that PG&E came out and fixed it that very night at 11pm, and strongly suggested many times that we turn off the power until they could come out and fix it.
Once PG&E had finished, all three of the problems went away. The bathroom light is working again (with the old bulbs, even!), the non-dimmable LED lights don't flicker when the dimmer is at maximum strength, and there's no more flickering when major appliances turn on.
My takeaway among all this is that Voltz may have great customer service and perhaps is pretty good at easy-to-fix things, but they aren't as thorough or inquisitive, and in our case they failed to even suspect what ended up being a rather severe problem. The other electrician was more humble and less self-confident... and that may have saved our lives.
(edit: After I posted, Voltz offered refund. Great C.S.!)