Postal workers in London struck for three days last week in a row over jobs and pay cuts.
Some 12,000 members of the Communication Workers Union (CWU) took part in the walkout.
Workers are set to walk off their shifts in different areas of London between Tuesday and Saturday of this week.
The union said Royal Mail was cutting jobs and pay despite a national agreement, and said the cuts would have a serious impact on working conditions and the quality of the service.
The government continues to back Royal Mail’s “modernisation” plans.
Workers are particularly angry at business secretary Lord Mandelson’s accusation that they are guilty of a “bury your head in the sand” attitude.
Martin Walsh, the CWU’s London divisional representative, said Royal Mail had turned down an offer of talks.
“We are up for change but we are not prepared to let
management or the government rubbish a great public service just so they can sell it,” he said.
Once again the strikes across London were supported by the vast majority of the workforce.
Many workers are angry at management’s use of “executive action” during the dispute—bringing in major changes to working conditions without consultation.
One London CWU member said, “This union cannot do any deal which does not resolve the disputes in those offices which have been attacked and executive action taken.
“We have seen the worst kind of bullying from managers. Post workers have been videoed on walks and threatened with executive action.
“Managers are being flooded into offices and workers are being moved between sections.
“Some people have lost £4,000 in overtime and are having to work an extra 46 days every year—yet we still hold the line and punch back with strike action.
“Management want to force us out unofficially in order to isolate us as the strikes are biting and working.
“But we are doing everything to stay legal and, while it is encouraging that a national ballot will take place, September seems a long wait considering the attacks we are facing now.”
London divisional rep Mark Palfrey said, “Our members are not going to allow Royal Mail to keep imposing change by diktat.
“We want the company to sit down and negotiate change with our union, but their current stance is giving us no other option but to take strike action in defence of our jobs and the future of our industry.”