Stiff glass

HI everyone,
I am new to the forum so hello to everyone.i have some strange issues going on with a commercial account that i have and hope someone has some answers?Anyway i have a convenience store account that i have where i clean 58 stores once a month and i have done it for about 18 years.The problem is all the employees became motivated at the same time and cleaned every piece of glass at all 58 stores. There is a hazy film swirl marks etc…on all windows.I have cleaned all the windows and it is extremely hard to pull a squeegee across the glass.Even if i razor and rescrub the windows it is still ridiculously hard to get the squeegee across.I can have the window looking crystal clear and rescrub it and squeegee it and it is still incredibly hard to pull the squeegee across.I had asked the employees what they had been using and they keep showing me the same bottle of cleaner at all stores.sometimes it is different,but for the most part it is the same cleaner.On back of bottle it says can be used on metal,chrome,and glass.I think that is a red flag there.If you can use it on metal and chrome i personally would not use it.You are supposed to dilute the cleaner although some stores say they do not.The convenience store i clean for has changed the chemicals they use 3 different times in the last couple months.My opinion is what they are using has gotten deep into the pores of the glass and has damaged it in some ways.i have tried glisten soap,dish soaps,abc slick,sorboglide etc…and nothing will restore the glide to the glass.i have talked to the person who oversees all the stores and they agree that the employees should not be using the glass/surface cleaner,but only a glass cleaner.The person who oversees the stores has no idea of how big a problem this is now.The work is 10× harder to do now.It feels like i am doing 120 stores instead of 58.I know will not understand when i have to raise the price on the stores.It would be a considerable increase.If anyone has any ideas what would work to restore the glide to the glass ,that person would be a life savor! I desperately need to figure this out.any ideas would be greatly appreciated!