Broadband providers are offering to slash customers’ bills by more than two-thirds if they threaten to switch to another supplier in the latest sign of the fierce competition in the market.

These cut-price deals are not publicised, but the companies will pull them out of the bag to prevent loyal customers signing up with rivals.

It has long been common for consumers to barter with their existing mobile phone or mortgage firm before they quit to try to get a better deal, but it now seems that the practice will soon become commonplace with broadband.

Mark Pavlika, 35, a human-resources worker who lives in north London, was offered a discount of more than two-thirds on his digital television, broadband and telephone package with NTL after he threatened to leave for rival Sky.

Pavlika, who had been with NTL for six years, had gradually upgraded from having NTL digital television to NTL broadband and landline, costing him £62 a month.

Two weeks ago, Sky cold-called Pavlika pushing its free broadband service. Pavlika decided to inform NTL of the offer.

“I just called them and said I was thinking of moving,” he said. “A woman said she would talk to their ‘customer retention’ department.

“About 10 minutes later she came back and said they would offer broadband, television and landline for £20 a month because I was such a loyal customer.”

“I’m a firm believer in haggling. This is one of those situations where if you don’t ask you don’t get. The market is so competitive at the moment that I think there are bargains to be had.”

A spokeswoman for NTL said it did not automatically upgrade customers’ accounts to cheaper deals.

“We assess each customer on a case-by- case basis. We would always recommend customers to check that they are getting the best deal,” she said.

Chris Williams at Uswitch, a comparison firm, said broadband providers were reluctant to highlight cheap deals so it was a good idea to call up and see what they would offer, especially since tariffs have tumbled.

In May 2005 NTL was charging £24.99 per month for 2Mb broadband. Since then, this price has fallen by 28 per cent to £17.99. Meanwhile, Telewest was charging £25 a month for 1MB broadband, whereas the cost now is only £14.99 for double the speed.