Tiscali has been forced to reverse a software installation on its bandwidth-throttling hardware, after it triggered complaints from customers who saw iTunes blocked during peak hours and other traffic slowed to a crawl.

Engineers have now rolled back the installation, so access should be returned to normal during this evening's "traffic management" period, a spokeswoman said.

She encouraged customers still experiencing problems to get in touch through the usual channels*. Over the last week users have reported newly-blocked ports and sub-dial-up speeds of 10Kbit/s between 5pm and 9pm.

The firm tweaked its opaque fair use policies last week via an upgrade to its Cisco kit. Complaints quickly rose as it hit speeds and blocked access.

The sudden deterioration of service brought howls of derision in Tiscali user forums. The majority of current discussions have headings like "painfully slow speeds" and "web ok, anything else = fail". Peer-to-peer, newsgroup and usenet traffic has also been affected.

The firm acknowledged the widespread issues five days ago. A company support administrator wrote on Wednesday last week:

We are aware that there is an issue in this area which is currently being addressed.

We will post in here when further updates are available. Sorry for any inconvenience caused.

As well as having an impact on gaming, this issue is a cause of peak time slow speeds and is currently affecting: iTunes access, VPN/FTP/RDP just to mention a few.

An update posted on Sunday doesn't give any timescale on a fix, only telling frustrated users that forum threads on the subject will be closed to new posts.

The spokeswoman assured us the cockup is now resolved. She added that customers will be informed on plans once engineers have identified what went wrong this time.

Tiscali is currently ranked fourth largest ISP in the UK with about two million customers. It operates at the cheap end of the broadband market, on some of the tightest margins in the business. In 2005 it was one of the first to clamp down on heavy users.

ISPs who have such policies maintain publicly that are in place to protect the majority of users' bandwidth. The truth is that the structure of the UK market for bandwidth makes heavy users very expensive for the ISP. The current Tiscali policy is here.

Bandwidth-throttling is now making waves in the US, where large ISPs are trialling it. ®

*Do get in touch with El Reg too, if you have the same trouble this evening.

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