I'm writing this, just half an hour after posting the whinge-fest that's the post below. I've written a follow-up letter to the Halifax (I'll let you know how that goes) and called Virgin Media about the £5 non-direct-debit charge.
And bugger me, if the nice chap at Virgin Media (call their customer care number, 0800 052 9403, not the customer services number, 150) didn't look at my bill, say: 'Yes, I don't think you should be paying all that, actually,' and offer to chop my bill by about £9. He said he couldn't actually remove the payment handling charge, but didn't think I should pay as much as I do for my 10meg broadband or the £1 itemised bill and said that from now on there'd be a 'loyalty discount' of £9 every month.
I think the phrase is: 'Result!'
I must admit, I'm a bit surprised at how easy it was - especially considering I've come away with a lower bill than before. Even the bloke (David, BTW - nice man) said that he thought that eventually the payment handling charge would be scrapped.
A little bit of my dwindling faith in humanity has been restored.