Credit reference agencies refer to the full electoral roll, which isn't available in electronic form (either online or on CD) to the general public. It's only available to 'official' bodies, such as the police, security services and those credit reference agencies. (The electoral roll available on sites like 192.com is only the edited roll, which excludes everyone who marks the appropriate box on their electoral registration form).
However you're still entitled to view the full roll in printed form at your local council office. (It's listed in street order, so you can quickly locate your house and see who's listed as living there).
If you've complied with your legal obligation to return your electoral registration form, the information on the full roll (both the printed version you can view at your council office, and the electronic version used by credit reference agencies) should be correct. If it's not your council office can supply you with a form to correct it.
Of course, credit reference agencies only run checks on people applying for credit. If the person buying the goods pays cash (or uses an existing credit agreement, such as a credit card) the retailer won't call for any checks. (I can't see why the purchaser would then give a false address, unless they're buying a TV, PVR or DVD recorder and don't want their address passed to TV licensing).
Chris