The complaints helpline was set up by the TUC

The TUC set up "It's Your Call" in order that workers could register complaints and address what it called the "sweatshop image" of call centres.

The industry currently employs more than 400,000 people across Britain, making it one of the fast growing industries in the country especially in areas of traditionally high unemployment such as south Wales.

Disposable nappy

Complaints received so far have mentioned bullying, impossible sales targets and late payment of wages.

In one call centre, workers were told that whoever went to the toilet the most would have to wear a disposable nappy.

The manager of the centre, which has not been identified, made staff sign a "toilet book" to check how long they spent at the toilet.

Other calllers talked about regular humiliation - like having to put their hands up like schoolchildren when they wanted to go to the toilet.

TUC general secretary John Monks said: "These figures show there are still too many centres using bullying tactics to pressurise and intimidate employees."

Companies have found skills they need here

The success of call centres in Wales has been varied.

In June last year, First Line Communications - which operated call centres in Cardiff and Swansea - collapsed with debts of �15m.

The 2,000 First Line workers lost their jobs and many were left unpaid.

The failure of First Line prompted a reappraisal of the call centre sector in Wales - but it remains a growth industry.

Call centre boom

Last October, Lloyds TSB announced it was to create 400 jobs at a new call centre in Bridgend.

The bank already had more than 2,000 customer service staff working in offices at Swansea and Newport.

In the same month, WTS Holdings also announced it was to create 60 jobs at a call centre in the former Kwik Save supermarket HQ in Prestatyn.

The TUC hotline can be contacted on 0800 032 0033.