Yeah yeah, I know, bugger off for months and only come back when I want somethung

been pissung about trying to join phone forums etc but know there's a lot of knowledgable folk her who might be able to help.
Finally got round to upgrading my old iphone 3g last week - had it about 5 years and was fine but figured I could probably get a lot more banf for my buck nowadays. Now using a Sony Xperia S. Smart piece if kit and got all the functions I want. Only trouble is I seem to be eating a hell of a lot of data. Was getting through around 100mb a month on the old phone - not a massuvely heavy user but checking into facebook/web browsing a few times a day. Now the same kind of usage seems to be eating over 100mb a day

. Did a quick test yesterday and found that opening facebooj, liking ine status and commenting on another - about 2 mins total - used up 9mb. How can it be such a vast difference for doung the same stuff? Got a data management app that keeps stuff turned off when i'm not using, but that doesn't seem tobe the main issue anyway.
Grateful if anyone can shed any light.