can i pay what i have used?

GST GST…because of you..i have to tight my stomach starting from next month..everything increase but my salary no increment!!!hahahha
So I think that I have to change my current telco data plan as it is a burden for me…every month commitment quite high..sumore i did not use so many data every month..so I m now actually is pay extra but I m not using it that much…very unworth la..