Inconsistent internet speeds

When service was installed internet speed was inconsistent, but I still had a decent speed, Now I am lucky to hit a hundred, a majority of the time I am below 75. Have followed all troubleshooting, have called to complain. Have reset cable modem several times, once in a blue moon it will work & I will get speeds between 100 to 150mbps. It’s like a switch & bait. Dishonesty, is the fastest way to lose customers & negative reviews. And to top it off, customer service tells customers that if a tech comes out & can not find a problem then you will be billed for the service call, so basically it deters customers from calling in to have a tech come out, let alone tech skill level is under par. It took several visits to find a bad cable at my house, every time I called customer service told me that I would have to pay a service charge. How ridiculous is it when the customer is complaining that there is an issue, you tell them they will be charged if the tech comes out & can not find anything wrong & then the customer continues to have problems. Or is Comcast creating problems for customers to milk them out of more money?