I have to say that it's (mostly) the carrier's fault.
I have the same issue sometimes with Airtel India, and I'm pretty sure this notification was turned off 2 years. [edit or maybe i just had a good data connection then]
Also, this issue is not consistent. I'm guessing what happens is: carrier sends usage alert when you "turn off" data + bad connection that keeps dropping => many notifications even though you never turned off data.
There are a few apps that convert USSD alerts to notifications - try these - but it would be nice if this was a built-in feature.
I have the same issue sometimes with Airtel India, and I'm pretty sure this notification was turned off 2 years. [edit or maybe i just had a good data connection then]
Also, this issue is not consistent. I'm guessing what happens is: carrier sends usage alert when you "turn off" data + bad connection that keeps dropping => many notifications even though you never turned off data.
There are a few apps that convert USSD alerts to notifications - try these - but it would be nice if this was a built-in feature.