Even though this turned out to be the cause of your particular issue, this type of problem with the Status Meter is the first instance I've heard of. The new meter definitely does have bugs, but again, yours is the first time I've ever heard of it causing a data usage problem. That's not the problem people have been experiencing with it. I highly doubt that Mary's data usage is being caused by the status meter, though anything is possible. It's most likely what causes excess data usage for just about everyone, which is something actually using the data that she has yet to discover, and there are a slew of possibilities, normally being discovered by process of elimination and vigilance.
This company needs reported because no other company is having these issues.
First, it doesn't help to post multiple complaints, then never answer any of the questions asked in those threads when help is offered. Due to this, further complaints have ZERO weight. They become meaningless.
As for the above quote, the reason why you don't hear about data usage with most other companies is because they don't have data caps. Without data caps, you would never know that a lot of data is being used. The main satellite competition has the same reports on their boards. Data usage is a bugger to pare down, and even harder with every device that's added to one's network.
But, with that said, in nearly every instance the data that has disappeared or is disappearing is actually being legitimately used. Finding what is using it is the trick. Various OS and App adjustments, programs like Glasswire, and even more expensive routers with special firmware are all things that help to nail down the root cause of the data usage. It's also a process of elimination.
Again, try answering the questions in the threads instead of just posting further complaints. Never accepting the help, but continuing to complain, is a bit ridiculous.