Piece
Tour Winner
Would be surprised if it really is the fit to blame. I understand where people are coming from about different swings for different days and I've been C/F'd before and not got on with the clubs (ironically TM R9's). However off 4 I'd have thought the technique was far more honed and it would be more a developing swing fault to blame. If he was unhappy for so long why didn't he go back to the tester earlier?
It can be easy to get a poor fit from reputable places, if the fitter is inexperienced. Unfortunately, I speak from personal experience. My fitter at the time focussed on two aspects of my iron fit - ball speed and launch angle. The new clubs were giving me increased ball speed and a better launch angle compared to my current - great I thought, not knowing too much about FlightScope data. I bought the clubs and suffered as a consequence for a whole year as I lost alot of distance - perhaps my technique had gone and I started to hit at, lost all rhythm and confidence. I started to research about fitting and then it hit me - I was suffering due to ballooning flight. I looked back at the Flightscope stats at that fit, and the spin rate was mega: 7600rpm for a 6i!!! Gah.
Within a month I had a proper Miz National fit and the spin rate was down to 6200. Distance and consistency was back.
I can sympathise with the OP to an extent, but only if the track data wasn't being fully considered at the time.