Mobile data is OFF on my device, data usage shows 0 KB, yet provider sees data usage each day. Help?

[Caleris]

First of all, my device is a Samsung Galaxy S4 Mini, running Android 4.2.2, and my provider is T-Mobile in the Netherlands, where I have a prepaid plan.

A few days ago I found myself without credit, much sooner than expected. This was the second time in a few months this happened, so I contacted customer service to ask what's up. According to them, my phone has continuously been using mobile data (which is not cheap on a prepaid plan!), as far back as they can see (~6 weeks). The strange thing is that I NEVER turn on mobile data on my phone.

When I look at the data usage in the settings, it tells me I have used 0 KB for the last few months. Since I noticed this (so a few days ago), I've also started monitoring the data usage using Onavo Count. It, too, shows 0 KB used. However, my credit is still slowly disappearing.

I have tried to turn on 'restrict background data', I have gone into individual app settings to try to prevent them from doing anything over the mobile network, but to no avail.

I have also ran scans using Malwarebytes and Avast, all of which came up clean.

I'm pretty sure this problem only started happening since around December 2014/January 2015 or so, before that I'd been using the same device+provider for about a year without issues. I've trying to see which apps have been installed/updated around that time, but unfortunately that's not so easy to track down.

I've also tried to check which apps have the ability to turn on mobile data by themselves, using Permission Explorer. Is it correct that the relevant permission in this case would be 'CHANGE_NETWORK_STATE'? If so, there's only a few apps that can do this on my device:
- ES File Explorer
- Facebook
- Messenger
- SleepBot
- SolMail

Do any of these have this as a known issue?

I really hope someone here can help, I've tried pretty much anything I can think of, and the people at T-Mobile customer service are not being very useful at all (they just won't believe I always have my mobile data turned off, I understand that is probably a common issue but please, I'm not totally stupid).

Thanks in advance!

Cheers,
Caleris

 

[B. Diddy]

Welcome to Android Central! That's frustrating--there's clearly some problem with how T-Mobile is measuring your data usage. Can you go to a T-Mobile store in person there, and talk directly to a rep? Show them your Data Usage screen, and compare it with their records.

 

[Caleris]

Hi, thanks for your reply! I already sent them screen shots of my data usage screen, but their answer is basically "our records are correct, your phone is wrong". I haven't had a chance to go to a shop in person, but it's the only thing I can still think of to do, too. Hopefully I'll manage to go this week Right now I've had them block all mobile data so I'm not losing money, but obviously that's not an acceptable long-term solution.