Tesco has reiterated the £1bn investment it is making in customer service after a survey ranked it the worst supermarket in the UK.

The retailer came last in a poll of more than 11,000 consumers by the watchdog Which?, scoring a customer satisfaction rating of just 45% and receiving poor marks for its pricing, quality of fresh produce, store environment and customer service.

Several of the shoppers, who were asked to grade the supermarkets on customer satisfaction and the likelihood they would recommend the store to a friend, described the Tesco experience as ‘unpleasant’. One said: “It’s stores tend to have surly staff and are littered with boxes.”

However, a Tesco spokeswoman said it had millions of customers and was looking at ways to help them improve their shopping experience.

“We have made a £1bn commitment to make Tesco better for our UK customers and since this survey in October 2012, we have had an encouraging Christmas and New Year and are delivering further improvements this year,” she said.

“We are focusing on improving the look of stores, giving customers great value and making sure they can get all the help they need, which is why we’ve recruited 8,000 more colleagues.”

Waitrose earned top place in the survey with a score of 82%, including five star ratings for its customer service and the quality of its fresh produce, while discount retailer Aldi came second (74%),and Lidl third 69%. In the online shopping category, Waitrose Deliver earned joint first place alongside Ocado.