Slow internet

The last two days my Internet has gone from 5MBPS all the way up to 600 and I’m paying for 600 but usually get around 150 which is fine but I was on the line with customer support yesterday took me 45 minutes to get a live person and then the operator couldn’t help me so they tried to get me to a technician that person came on the line and apparently I turned away for 30 seconds after being on the line for almost an hour and it said call ended due to inactivity. Needless to say my problem did not get resolved. I still have slow Internet speed this morning and I don’t really wanna spend another hour trying to get to somebody that might or might not be able to solve the problem. I know that on the 25th which is in two days they’re supposed to be doing work in my area so I can only assume that it’s Xfinity doing something because I haven’t had this problem before I went through all the steps check my router check my modem restarted the modem turn it off turn it on all the stuff, but it does not seem to be a problem at my location. Would appreciate some help.