Xfinity is such a scam company

I recently moved to a new house and signed up for Xfinity internet. It's been nothing but problems, internet keeps dropping out completely. We've had 2 technicians come out, each one seems to know less than nothing. First one said it was a bad splitter, so he replaced it. Internet kept completely dropping out, customer service said it was a bad modem, so we swapped that out. Internet lagging like crazy, we're paying for 1100 mbps, only getting 400. Second technician said the first one didn't do a good job, replaced the splitter again and said that our internet is signal is too close to the window and its sending the signal out the window instead of in the house. he also said the because the modem is next to an exterior wall the signal is being sent into the wall so we should be happy with the 400 that were getting, then Xfinity should give me a refund for the higher speed that I'm paying for. Also, our main TV is right next to the modem and it lags out constantly. What I am getting from the last tech is that the modem and pods choose the least convenient direction and just sends its signal in a linear fashion, so we can never get a proper connection. All of this is complete [Edited: "Language"]. I am so tired of the customer service "resetting" the modem and running us through a gauntlet of "tests" just to schedule an appointment that they want to charge us for, for them to come out and not do their job... Can someone with actual information please help me so we can actually watch tv or browse without lag??