Extremely high data usage on home internet

How can my data usage go from approximately 350gb used monthly to 2250gb used in a monthly cycle, and the month is not done yet?

My area was hit by Hurricane IDA at the end of August. My internet and cable was out for about a month. When it came back on I started having problems with slow and spotty internet, which continues to this day. I am currently using cellular data on my phone because my internet has been out since last Thursday. It’s been a week. 

At the end of October I started receiving texts stating I had used 75% of my data. Within an hour I received messages stating I had used  90%, then 100%, then I was over my data usage for the month and collecting overage charges. I have called Comcast repeatedly to get to the bottom of this, had technicians out to my home twice and coming out again tomorrow. I’m even accumulating data usage with no internet connection. Please if anyone else is having a similar problem let me know. If I can’t solve this problem, I’ll have to say goodbye to Comcast.