Way vtec works (I'm not talking down more like talking out loud)
oil pressure must be over 55 psi
engine coolant temp must be over 140'f. Iirc
speedo must operate (vss signal)
solenoid must get 12 volt signal
If all those work car will hit vtec. Basically aem reads all those factors then tells the solenoid to open at 55psi and xxxx rpm to switch into vtec. Oil pressure basically gets released when the solenoid opens down rocker shafts that move pins into position to lock in the vtec lobe on the cam. Yours wasn't doing that.
yOur car wouldn't switch at all. Even though all the above was working. We put a constant 12 volt to you solenoid to get it to manually open it clicked meanig the solenoid was working. Aem was switching from lo cam to high cam so aem was fine. Oil pressure was fine
that means there was something mechanical not operating. Like the vtec rocker arm/pins . At that point I told you I didn't know enough about s2000 heads to know what activated like a b series. B series is rocker arm driven wih pins s2000 and k series is roller rocker. At least I was honest but like I said it was definetly mechanical.
If that mechanical problem fixes itself I agree weird but not the weirdest thing I have ever seen. I don't think you got ripped off I think it was just something that We diagnosed , didn't find the problem in an hour and you left