I have had the same problem with my new Pool. For the first 6 month I have used a Pool Service, but they never told me that there is a problem with high PH and low free Chlorine. Then I have started testing by myself and checked the complete System, here I found that my Chlorinater was running in Winter Mode. I changed to normal mode, since the problem with low Levels of free Chlorine was resolved.
Then I cleaned out the Balance Tank and Gutter, measured additional Salinity, Cyanuric Acid ,Alkalinity and Water Hardness and brought all step by step to the required Levels.
All has taken a while but now my PH is always between 7.3 and 7.8, here I add always 1 liter of Muriatic Acid to lower PH what is good for 8-10 days before I have to add Acid again.