A lot of this is a Cameron screwup though. He changed the number system to make it look like the economy was doing a bunch better, then as a result of that it turned out we'd been underpaying the EU - this is, to clarify, a regular readjustment, it's just that because of our figures changing we've turned out to have like a decade's backlog. Also the treasury have known this was coming up for ages and now they're acting like it's some travesty - this readjustment happens every year, it's just that most years we've been given a rebate from it so everyone's ignored it.
Of course 2 billion is a lot of money, and the EU would have been smarter to smooth over it by making the payments an incremental upward adjustment of future payments not a lump sum. But this is at heart a politically manufactured crisis.