Looks like you're in UK - your contract is with the retailer, your claim is against them under the Sof Goods Act, and they need to prove you damaged it.
The Sony practice of charging more for repairs than sale price is, sadly, not unusual - they don't wat to repair them, basically, toom much hassle I suppose !
But concentrate on the retyailer.
And if you really can't face a Small Claims Court claim, do check your Household Contents Insurance - most decent ones have an accidental Damage cover, which you will only pay your excess figure on. ( I know this, after running over my own nice new camera !
Don't ask, it's too complicated...! ).