Worst service by Aqua Soft water purifier

I have one Aqua Soft RO- system.On 9.8.2016 I found that PPM of filtered water was 105,I requested their Service Engineer to replace its Membrane and both candles .After number of reminders they came on 12th Aug and changed the above and charged 3150/-.On asking for bill they said that do not have bill book.On 13th morning I found that water was leaking in upper part of the body since then dozen of time I requested them to attend it but inspite of promise they did not turned up till 1800hrs/16.08.2016