Etisalat — elife service charges

I got service charges because my elife internet was not working due to change device as per etisalat and i was asking from etisalat peoples that make sure i shouldnot get any charges because you are the one who change the internet devices after that we are facing internet issues, kindly take a not to help me to reverse the service charges of AED150/- which is not acceptable, i had very very bad experiance from etisalat always, because always they are saying something & doing something else,
Seek your kind help to reverse the charges.
regards
Muhammad Mohsin Zaheer
[protected]