Hospital bosses have drafted in extra staff to deal with complaints from patients.
Brighton Health Care NHS Trust wants to improve its response times so all complaints are dealt with fully within 20 days, in accordance with NHS guidelines.
About 32 per cent of cases are currently investigated within the time period, which the trust says needs to be improved as soon as possible.
The trust, which runs Royal Sussex County Hospital in Brighton, dealt with 210 complaints and negative comments between July and the end of September this year, the same total for the previous quarter.
A significant number of surgical complaints were about delays and cancellations in obtaining either an appointment or a date for admission.
The number of calls praising the trust and services received in the same period has doubled to 172.
A report to the trust board says the increase is due to more efficient use of its database system, which logs all calls and enquiries.
The report says increased efficiency and extra staff in its complaints department should lead to a marked improvement in response times in the next six months.
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