Incompetent Contractor

Forgive me ahead of time if I don't nail all of the technical terms.. My husband and I are paying for 100mbps of internet and lately it's only been functioning ~ 25mbps. With us working from home now we've encountered some hiccups so we've requested Xfinity come out to take a look at everything. 

We received a text message alert telling us the person was outside, when he wasn't. Then we received a message from the guy saying he'd be here in 20 minutes..

30 minutes later the guy shows up, takes a look inside our house, then wants to check underneath our house and outside. When he comes back inside he resets the modem (which had already been done the night prior with someone over the telephone and it didn't work.) He then proceeds to tell us that we need to be closer to the modem and it will work better. Our house is less than 1200 sq ft. My husband and I work on separate ends of the house since we are on the phone frequently, and our modem is in a NURSERY. We're not going to work huddled around a baby.

He then says that he will likely need to re-wire our backyard (mind you he never attached any sort of device to check how efficient the wires were working in the first place). When my husband and I pushed back and questioned why they wouldn't replace the modem first, as that seems to be an easier solution to try before re-wiring the house, he fumbled around his words as he clearly didn't know what he was talking about. He said that he needed to step outside and call someone. Then he LEFT WITHOUT SAYING A WORD. 

My husband called him and asked where he went and he said "they're going to send a professional." My husband tried calling again and his number was blocked??

Ever since our internet has been flickering on and off while my husband and I are trying to work. This wasn't happening before so it would appear that this man did something to make that be. 

Is this how you do business? We've been with Xfinity for years! Was this a contractor? Did he leave without notice because he wasn't going to be able to bill the highest price if we only wanted to replace the modem? We've even questioned if this man was legitimate at all.. Some guy in a white van comes inside our home, takes a look around, does nothing to resolve our problems and then leaves without saying  a word?? Not only do we still need our internet fixed, but now we're concerned about our safety as this man clearly did not know what he was doing and was highly suspicious.