Except for Netflix, which may transfer higher quality images with faster speeds, little else would increase the volume of data, simply because your speed was increased. If you previously consumed less than 200 GB, and this month have consumed over 300 GB in two weeks, the most likely culprits are:
change in use by users on your network
apps consuming more data than usual
operating system updates
someone outside your home siphoning your Wi-Fi
You can solicit the help of your family, by resetting all devices and your router to zero data use, and see if there are any indications of usage spikes.
I would recommend that you start signing on to your My Telus account daily and recording your data usage. I experienced data spikes earlier this year so started doing that to see if I could identify any unusual activity. My spikes were much higher than yours though. After working with Telus for a month or so they thought that the modem was reporting false data on my usage and replaced it with a new one. I have not had any spikes since this change.
My average daily use (my wife and I) is about 8Gb. This includes about 5 hrs streaming Spotify premium and 1 Netflix movie. If we watch a 4K movie then it bumps the data to about 12Gb.
A change in your data usage can only be caused by 2 things:
Until you investigate and eliminate 1 as the source TELUS will likely not do anything about 2. TELUS really can't investigate 1 for you.
What to look for:
- Any new devices in your house? i.e. media streaming devices, etc.
- New applications, versions, settings on those devices? i.e. OS software update downloads, BitTorrent, etc.
- New users? You mentioned guests. Have you given out your WiFi password recently?
- New user behavior? i.e. video conferencing, on demand program viewing, etc.