seems I'll have to convince him to change ISP
Well, you didn't mention it, but I assume you've tried to resolve the issue through AOL support channels with no success ? A bit far fetched, but it might, just might, be some sort of temporary problem ?
How good Sky are I don't know, but I haven't heard anything bad about them myself.
Sky bought Easynet, who were a very well respected business service that also ran the excellent UKOnline service for home users.
I've not had any experience of the Sky products for home users, but the products sold for businesses under the Easynet brand continue to be excellent.
If Sky give you the option as a home user, try to ensure you're getting an LLU broadband line. LLU on the Easynet network is so much better than the BT Broadband that every man and his dog sells as a re-branded product.