Is VPN using all my data and slowing my computer?

Around May/June, I started receiving Norton pop-ups for VPN permissions. The same month, all my data was used up. When I purchased 5 extra blocks of 1GB data each they were used almost immediately. The computer has been running slow ever since.

I have had the same data provider since 2016, so this is the first time since 2016 all my data has been used. I don't do any major downloads such as movies and neither does my partner. 

I have chatted with Norton reps.

Various "solutions" were to:

1. set a data limit in the data usage area,

and 2. to change my VPN to a different country which for me means across an ocean. The agent said that was OK.

A third chat last night got cut off by the agent when I asked about removing certain files.

I'm at a loss as to what to do besides turn off the VPN to see if it changes. I ended up upgrading my data to the highest level to try and alleviate the problem, but I have kept a data limit so I don't have all my data used up as I have a business to run.

After all the data on the computer was used up last month, my partner used his phone (also with Norton) as a hotspot. All his data got used up. 

Could the VPN be using all my data? Could the VPN be slowing my computer? I have gone through all Microsoft procedures on speeding up/ cleaning the computer.

Basically, I can run one app at a time and even that is sometimes very slow. If I try to open multiple tabs at once, it doesn't work. I've never had the problem until last month. My memory usage is at 75% which is high, but shouldn't be causing the issue.

I note that Wire guard was installed around that time by Norton as I checked in File Manager. I note that it has the highest data usage of apps listed on my computer. Data usage for Wire guard is always shown maxed. 

I have 8GB RAM with i5-7500 CPU, 3.40GHz, 64 bit OS, x64-based processor

Any suggestions would be very much appreciated. 

Thank you