To be able to do coil split in the AV3, you'll need to replace the 3 way toggle switch with a rotary switch or replace one or two potentiometers with push/pull types.
Their frequent guitar tech's knowledge base is quite low regarding guitars. I'd find it amazing if they can sand down worn/dented fret wires without ruining intonation at individual frets
Someone at an electrical repair shop would be able to do it in a few minutes as long as you have the wiring diagrams for the pickups & the AV3. If you can't find the wiring diagram on the Greg bennett website then since it's a Gibson styled guitar so maybe they copied the wiring layout of one exactly the same. Open up the cover on the back & start tracing to see if you can find something same or similar to normal gibson wiring. That should solve some wiring problems or even present a better way of tiding things up of the stock wiring. If you do take it to such a place then make sure the pole pieces are in the right direction, sometimes changing the orientation of the pickup can change the way it sounds.
Hope you can find someone to do it for you. You could do it yourself & it's fairly easy work but since you haven't soldered anything before then don't bother doing it as a first time experiment. Now would be a good time to buy a soldering iron & some solder and try practicing/building soldering skills on some old worn/broken/bad/non functioning instrument cables. Easiest would be to buy some MX plugs & some house guard wire and start practicing on those, after awhile when you get good at it you won't be in this situation again.
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