Network Virus?? HELP!!

I appreciate anyone who could give me some advice on how to fix a network virus I have. Recently there was an increase in our internet usage. Usually, we do not go over 700 GB but this month it was almost 1200 GB. When I went to the Netgear Genie I looked at our logs and I saw some DoS attacks. Such as:

  • [DoS attack: Ping Of Death] from 92.131.203.0, port 0
  • [DoS attack: Teardrop or derivative] from 92.131.203.0, port 0
  • [DoS attack: Illegal Fragments] from 92.131.203.0, port 0

When I contacted Cox, they told me the only thing they could do to help me was to purchase their Customer Care plan or something along the lines of that. However, when I had a similar problem last year, the representative on the phone gave me the contact information for BIT International? Personally, I never heard of the company but decided to give it a try. They seemed to fix the problem last year, but after accepting another payment (I spent over $400 now at BIT International) they took the payment and said they would call me, but never did. I know that I am going to have to call them back which is not a problem, but does anyone know what else I can do to fix the problem? I have changed the name of our WiFi, changed our password and they installed another antivirus on the computer...

Is there anything Cox can do to fix this problem? I am currently using a Netgear AC1900 Router. Any suggestions would help as this issue has been going on for I have no idea, it could have been months and I do not know if it is considered serious or not? Thanks!!