Thousands of patients were affected by hospital appointments chaos caused by the botched installation of a new computer system.
The full extent of blunders by Mid Yorkshire Hospitals Trust is revealed in a report which bosses at the organisation tried to keep secret.
The trust, which runs Pinderfields, Pontefract and Dewsbury hospitals, was ordered to reveal details of in an internal investigation in a ruling by the Information Commissioner.
The report shows that during a five-week period from October 1, 2013, 16,437 appointment letters were not printed, affecting around 9,000 patients.
Patients received out-of-date reminders saying their appointment could be cancelled unless they contacted the trust within a six days –then could not get through on the phone.
Others turned up for their appointments to find the hospital was not expecting them after the automated appointments system was installed that September.
At the time, Mid Yorkshire said the installation of the new system in September 2013 had cost almost £1m. The report also reveals problems with appointment letters the previous year.
In July 2012, 749 letters were not printed, but the error was not detected until August 3 when trust staff noticed an increase in patients not attending appointments.
Then in August 2012, no letters were printed on three occasions. Around 7,000 patients were affected in total.
Problems with the new system happened during a management restructure which saw experienced staff leave the trust.
Among reasons for the chaos was “lack of handover from outgoing staff to newly-appointed staff”, the report said.
There were recruitment problems and knowledge and experience among appointments centre staff were “depleted”.
Letters were printed and sent out by private provider Synertec. The report said Mid Yorkshire had no specific contract with the company, and there was a “missed opportunity” for Synertec to discover that letters were not being printed.
In July last year, Mid Yorkshire said the appointments chaos had been sorted and 95 per cent of calls were being answered withing three minutes. The trust has said no patients came to harm because of appointment delays.
Chief executive Stephen Eames said improvements had been made following a Care Quality Commission inspection last year.