Installation Fee Charged

I signed up for services via the internet. Upon choosing my plan there was no option to have someone come and install. I opened up chat and explained that I did not know if my house had comcast services already and that I didn't think self installation would work. The person on chat said that if it didn't work they'd send someone out and waive my fee. I waited a few days for a coax cable tried installing and spent an hour on the phone with someone troubleshooting all for them to tell me that it wasn't working and they'd need to send someone out. I told the person on the phone that I already knew this was an issue and my time was wasted by having to install myself and that I was already promised a waived installation fee. She told me she'd schedule someone to come out and that I need to agree to the installation, but that the fee would be waived after I agreed. Well now I have that $70 charge on my bill and I called and they said too bad you agreed to it. So I have a screenshot of the original agreement to waive installation plus your representative basically lying to me on the phone to get me to agree to the installation even though they said it'd be waived. How horrible to treat customers this way, I had ATT previously and their customer service did not treat me like this, no one lied. The service wasn't great which is why I switched but they are an honest company and told me like it is. If someone could help me that would be great.