The data that is consumed is always measured using Globe's meters and not a third party like our device or some other meter. Unfortunately, it is quite hard to dispute Globe's measurement as they alone know the actual consumption which may not be the same as the reported one as there would be clams by Globe that there might be other charges still to be reconciled since the last inquiry.
Again it is unfortunate that all our telcos (not only Globe) apply this method.
By the way... Supersurf 50 is supposed to be unlimited surfing for 1 day yet the subscriber is being limited to 800Mb a day!
They might have just stated Php 50 for 1.6Gb of surfing for 24 hours.... The perils of marketing.