I clicked on your website link to see what you are doing in terms of carpet cleaning - but the links broke.
I have a number of fluids and powders I an use.
Mostly its Solutions Cornwall M-Power (Nemesis Super from Restomate is similar), pre sprayed, agitated, dwell time, then just before rinse spray over with Solutions Heavy Duty if needed - even on wool knowing I ma going to give the carpet a good rinse.
I also have used, and still got, Chemspec DFC210, Prochem Pure Clean which are considered pretty safe.
Going up the ph scale if Heavy Duty is not cutting the mustard, I might try Prochem Double Clean, or Prochem Powerburst (which with perseverance seems to be working for me at last). Definately an acid rinse like Hydramaster Clear Water Rinse.