Trade unionists warned that the future of post offices was under threat today after trials suggested that Con-Dem outsourcing plans could wreck vital aspects of the public service.
Under the so-called Post Office Locals model retail outlets would be able to deliver some postal services from their existing cash desks rather than having to provide a separate post office area with dedicated staff.
But a study by Consumer Focus based on mystery shopping at more than 100 branches trialling the model highlighted "widespread evidence of inconsistent and inaccurate" product and pricing advice.
More than one in six customers surveyed by the watchdog said they could not access a service which should have been available and more than a third complained about lack of privacy.
The Consumer Focus study also found some branches were capping the amount of cash or benefits a consumer could withdraw, while others refused to make any cash payments at all.
"This poses a potential risk for older and vulnerable consumers, who rely on post offices to access their cash," researchers warned.
Consumer Focus chief executive Mike O'Connor said the new model had potential benefits such as longer opening hours and greater convenience, but he argued changes were necessary to make it more reliable.
"The report shows a mixed picture and that further work is needed to make sure the millions of customers who will be affected receive a good quality and reliable service," he said.
"Everyone will welcome longer opening hours, but they would also expect most core post office services to be available."
Mr O'Connor called for changes including an overhaul of staff training, stricter monitoring, support and compliance processes.
CWU general secretary Billy Hayes welcomed the report.
"But we are less optimistic that it can be made to work than the watchdog," he said.
"The report confirms our concerns that the locals model threatens the post office network and the services which communities rely on.
"High quality post office services are unlikely to be delivered by a retailer whose primary focus is the quick and efficient sale of his or her retail products - whether that's petrol, cigarettes or groceries."
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