Since you purchased it on an egg card, I assume that you have actually paid for it as a consumer not a business. (Assume that the card is in one of the directors / partners names and does not say the company name on it).
If it has, you may have purchased it as a consumer and not a business. I would go back to egg and state that you wish to excercise your rights to return the goods to dell under distant selling regulationunder and that under section 75 of the COnsumer credit act you are seeking redress from them since Dell will not refund you.
IMHO this is a bit of a grey area, but if you have purchased it in your own credit card, you may have extra rights - its worth a try.
You can also try for further advice
http://www.dellhell.net/