Is it possible to top up for date usage before refresh date on allowances. I've requested more data next month ( switched up tariff ) but could do for travel on hols ( in the uk ) as google maps sucks up data. My refresh date is somewhere in the middle of our holiday. I know i can pay for more airtiem but will this automatically cover date in advance...or I'll end up paying the daily charge. Think can thenget wifi at holiday destination so can survive once there.