Irate Tivo customers will now be able to delete so-called spam TV from their boxes after the company decided to change its policy.

The rethink comes after existing customers made their complaints about the unsolicited content public.

Tivo devices can record TV as well as 'predict' which programmes are likely to appeal to individuals based on their viewing habits. But there is also a section on the system's hard drive designated purely for 'Advanced Content'. This includes software downloads, full programmes and channel highlights – all provided by Tivo's sponsors.

Until now, this pushed content – basically junk TV – was undeletable for seven days, so even if viewers had no interest in it, there was nothing they could do about it.

Now, Tivo has binned its seven-day rule in favour of a more flexible approach.

"The period is variable. On a recent recording it was seven days, although we will be trying different durations to determine the optimum period," said Andrew Cresci, vice-president of Tivo Europe.

Cresci also answered another concern regarding this sponsored content, reassuring customers that it does not take up any of the promised 40 hours of recording space offered by the Tivo's 40GB hard drive. "The captured programme will never impinge on the user's 40-hour recording time," assured Cresci.

Tivo has defended the sponsored programming, claiming it broadens user's viewing lists. But its real purpose is to keep sponsors happy. "It is intended to promote content that the sponsors choose" admits Cresci.

Although this section is necessary for Tivo, which needs the financial backing of advertisers, experts worry that if it doesn’t provide an opt-out clause for viewers it may end up isolating them.

"It won't do them any good to send spam programming which cannot be deleted as it will only alienate subscribers, not only to the company but also the system," said Arash Amel, TV analyst at media research journal Screen Digest.