I dont really know the maths, but in my laymans brain isnt the fuel surcharge still too high given that oil prices have almost halved.
Don't forget that BA and some others bought fuel forward and so avoided paying peak prices, so the price has to drop some way before it gets to what BA etc. have been paying. Depending on the details of the contract, they could be obliged to pay more than the current spot price for some time yet.