Supermarkets are being investigated by the Office of Fair Trading(OFT), for allegations that they are overcharging online shoppers.

The probe follows complaints that internet shoppers are charged higher prices that those advertised and that they are charged for premium products when cheaper ones are delivered in their place. Complaints also highlighted the unsatisfactory condition of fresh products that were too close to their sell-by date.

Concerns have also been raised regarding the issue that online grocery sites provide only guide prices for orders. In addition, one of the biggest complaints by shoppers is that the sites do not tell customers when the goods they have ordered are not available, which is when substitute items are chosen.

Tesco has said that its customers could choose not to have any substituted items if their order was not in stock, while Sainsbury also pointed out that fresh foods close to their sell-by date would not be included in online deliveries, as reported in media coverage today.

Ironically, the Grocer 33's regular online shopping survey has seen fulfillment issues improve dramatically over the last couple of years.