Billing issue!

We had an internet outage for the last four weeks and assuming it was a problem with my router I rent an xfinity router and yet the internet outage persisted and two times technician visits , I was charged a 100$ for one of the technician visits … I am shocked and frustrated despite spending several hours on the call and trying to do what ever I can,  at my end to restart n reboot the modem(the one which I ve taken for rental) , you hold me liable for those charges ! I spent at least two to three hours each day trying to fix the internet with no luck . It works only for few hours and off . I registered for college online this year and much to my dismay spend two to three hours trying to resolve and when I schedule a technician visit , you ask me to pay a 100$ , literally the day after his visit I again had an outage for several hours for two days continuously … and this technician visit was a follow up after my first technician visit in about a week where the issue persisted . I kindly request you to do the needful and waive off the technician visit charges I have nothing on my end which I own .. it’s all your equipment your cables and still you making me liable to pay the charges is not the way you serve your customers …