Hi John1111,
When it comes to large uploads, the usual suspects are:
- Virus & Malware: Make sure your security software is up to date and scan each device
- File sharing: This includes programs such as Skype, Cloud backups, torrents etc
- Large emails: If an email with a large attachment is continually trying but failing to send this may quickly accrue upload data for each attempt to send
- Mobiles & tablets: Some settings can allow data usage in the background for cloud backups and photo sharing
- Shelly