This code doesnt seem to be account specific so here is what you have got to do to get the 160gb hard drive for just £39.99. In order to get the deal you need to do the following:
1) Go to http://svp.co.uk/products-solo.php?pid=2348
and put the Freecom 160GB hard drive into your shopping basket. The items is labelled as £49.98 on the SVP website.
2) Add any other items you need from the SVP website.
3) Proceed to the SVP checkout and enter the voucher code freecom3999 to get £10 off the price of the Freecom 160GB hard drive.
Hope this helps. :)