I don't like the way Carphone Warehouse never leave you alone after buying from them. They're always calling friends of mine giving the hard sell.
I find quite the opposite, I asked them to remove me from marketing and haven't heard a peep from them at all.
Especially if you're buying sim-free - There's no contract end date, so they can't call for an upgrade when the time nears which is usually what they are more interested in!