With the reports today that MESH Computers is in difficulties, many PC buyers will be concerned about making an online purchase, and what to do when it goes wrong. Here's how to protect yourself when an online purchase appears to have gone wrong.

The Distance Selling Regulations say that a company must deliver goods ordered online within 30 days of the date of order. If this does not happen you may consider the contract void, and you have the right to demand a full refund. The seller must make that refund to your card account within 30 days of your request.

If the repayment is not forthcoming, and you have taken all reasonable steps to contact the seller - without a result - you should contact your card provider and ask them to begin a charge-back process. This means that the card company will credit your account in full, and then take the money back from the seller's merchant account.

A small claims court judge will expect you to have taken those steps before resorting to a small claims procedure, so it's in your interests to get things moving as rapidly as possible.

Write to the company concerned, telling them that unless the money is credited to your card account within seven days you will take further action against the company for recovery. In the meantime contact your card provider, and tell them what you've done.

And finally, don't forget to log your complaint in PC Advisor's Consumerwatch Forum. For more detailed advice, read 'How to shop safely online'.