Your phone shows more mobile data than your carrier’s app. Before looking for an app that used too much, check whether the two totals describe the same interval. A larger number is not automatically a contradiction.
Here is an illustrative example: the phone’s record starts on 1 September, while the carrier’s current period starts on 20 September. Comparing them on 6 October mixes different lengths of time. Subtracting one total from the other does not reveal unexplained usage.
Write down what each counter covers
On iPhone, open the mobile-data section of Settings and inspect the usage statistics. Apple documents a manual Reset Statistics option. Before using it, record the existing total and any displayed reset date; do not assume “current period” means your billing month.
For each screen, note the period’s start, the observation time and the selected mobile line. In the carrier’s app, also check whether the figure concerns one line or a shared plan, and whether it is data used or data remaining.
Preserve a comparison you can explain
Keep the original figures. If the carrier shows when its information was updated, record that too; otherwise ask about its reporting delay rather than inventing one.
For the next comparison, choose a clearly defined interval. Reset the phone’s statistics only if you deliberately want a fresh local count and have preserved the previous information. This is not a phone restart or a reset of its network settings.
If comparable periods still show a difference, give the carrier the dates, line and figures. Apple directs users to their provider for the most accurate current-period usage. Do not try to settle a billing discrepancy by repeatedly clearing the phone’s counter.