Ordered a Computer Network Management Device from Tesco Direct that was listed on the website for 20.00 which I thought was a good price and would allow me to control my server at home and powerconnect switch.

I have ordered and paid for the item and received something completely different to what I ordered.

I contacted them and was told that the product was listed incorrectly and that whilst they do have the Item that I ordered, it was considerably more than 20.00 so they were not willing to send out what I had initially ordered.

Is a company allowed to do this?

My understanding is once an order is placed and a receipt / proof of purchase obtained then the retailer must supply the ordered goods for the price paid. If the price was listed in error then tough luck to them?

How would one go about challenging this?

I'm happy to suck it up and pay the full price,

but when someone orders an item they would like to think that's what will turn up.

Found this in their terms and conditions

3.2 The Seller reserves the right to revise prices prior to dispatch of Goods to reflect any indirect or direct increase in costs to the Seller but if the price has been paid in full prior to dispatch no price revision may take place without the prior written agreement of the Buyer.

So I could insist they send the correct item anyway as I have paid in full and have a receipt?

Also in their terms and conditions

14.3 Every effort is made to ensure that prices shown for products are correct when the products are added onto the Tesco direct site. If, by mistake, we have under-priced a product, we will not be obliged to supply that product to you at the stated price, provided that we notify you before we despatch the product to you. In those circumstances, we reserve the right to cancel your order. In the event we cancel your order, we will notify you and give you a full refund on any amount already paid for that product.

As the item was incorrectly priced, I think this term will be the one they rely on. Either you can pay the full price or the order can be cancelled and your money refunded. You should not have to pay any return costs etc for the item they did send.