National officials have apologised “unreservedly” after the handling of thousands of complaints about GPs and dentists was delayed following the handover to the reformed NHS system.

NHS England, which is now responsible for dealing with primary care complaints from across England, built up a “backlog” after 1 April as a “national contact centre” set up in the West Midlands proved unable to cope with its workload.

For more than two months it failed to quickly process the large numbers of queries and complaints it received.

Previously they were handled locally by staff at 151 primary care trusts.

The exact number of patients’ primary care complaints affected by the delays is unknown but it appears to have totalled about 3,000.

NHS England has now improved its processes and is dealing with the backlog. However, HSJ understands 1,126 complaints are still “awaiting action” and a further 2,185 are currently being dealt with.

For a period the centre was not accepting concerns by phone, so all patients had to write or email, making it harder to complain, particularly for those with visual or physical impairments or learning disabilities.

The problems were highlighted in a letter sent by Thurrock Clinical Commissioning Group to NHS England in early July. It says the “backlog of cases waiting to be investigated” is “unacceptable in terms of customer service” and ability “to resolve concerns promptly”. It also raises concern that “intelligence” from the complaints cannot be used locally.

A response letter from the NHS England Essex area team − one of the 27 local area teams nationwide − says the backlog for its patch at its height was “in excess of 100 cases”.

NHS England said much of the backlog was being addressed and the process had been improved, with the national centre now passing complaints more quickly to local teams.

It said in a statement: “There were some challenges in the service’s first months of service and we would like to apologise unreservedly to anyone who had a delay in receiving a response from us.

“New processes and additional staff have now been put in place and we are working over the longer term to ensure there is always enough capacity in the service in future. Staff across the national and area teams are working hard and are progressing well in addressing any remaining backlog.”

NHS England deals with complaints about all primary care − GPs, dentists and ophthalmologists − if patients are not happy with the provider’s initial response. The vast majority concern GPs and dentists.