Xfinity Assistant Won't Let Me Scheule tech visit to my place - keeps making me troubleshoot

I was having bad wifi issues. Comcast said I needed a new modem, but it only made things worse. I talked to support on the phone, and at the end some tests were running but agent said if its not better when done, call back to scheule a tech to come out to you. But every time I try, or try on the assistant, it makes me do the same thing over and over. Restart the modem. Then its better for an hour or two, and the assistant says all is better. But couple hours later starts to get worse again. Then I call and same thing over and over. This new Xfinity assistant is [Edited: Language], it saves Xfinity money and costs us time. Please help.