Jokay
Just read your June reponses, as you don't want a window cleaner you have 3 chooses.
1 Buy a wfp system and do yourself, One for your needs will cost you £400, plus you will need to change the resin when it exhausted, this will cost you about £90.00, it should last you at least a year, unless you have very high tds readings.
2 Buy a triple set of ladders and do yourself, if you get someone else to do them, beware that you are liable if they have a accident.
3 Have dirty windows.