A patient waited 11-and-a-half hours for a call back from a clinician after ringing up the NHS's new non-emergency 111 service, it has emerged.
The patient was based in the area covered by South East Coast Ambulance Service (Secamb).
The details came from the NHS's 111 Easter SitRep internal report, showing how long patients had to wait for call backs between 26 March and 1 April.
Secamb disputed the 11-hour figure but said safety was its main priority.
The report was first published in medical industry magazine Pulse.
The new 111 non-emergency telephone advice line is expected to replace NHS Direct in dealing with non-emergency calls in June.
The service is being rolled out in stages around the country.
In Kent, Medway, Surrey and Sussex, it is being piloted from two call centres in Ashford and Dorking run by Secamb.
Charlie Elphicke, Conservative MP for Dover and Deal, said: "It's very hard for people to get emergency appointments, fast appointments to see their local GP.
"On top of that, you then phone the 111 service, if it sounds serious and they can't help you on the phone or they get to the end of their 'what you should do' chart, then they say 'go to hospital'.
"People are being funnelled into A&E services and East Kent Hospital is saying A&E's are now chock-a-block with people.
"It's not a great system, not a great situation and it does need to be sorted out."
In a statement, Secamb said: "Patient safety is our number one priority which may account for longer than average call back times for our region.
"Secamb is contracted to undertake three attempts to call back a patient. These are all included in the call back time data, whether they are successful or not.
"In addition, if no one answers on these attempts, and we feel it is important for us to speak to the patient because of the nature of their call, we will leave that call in the queue for a clinician to try again later on.
"These are also included in the overall call back time.
"We are currently looking to establish whether the data we are providing for this is in line with other organisations."
The spokesman said the implementation of the phone line was at a "very early stage".
"We recognise that there is a need for improvement which is why we are working closely with commissioners to resolve any issues," he added.
"Secamb, along with all part of the NHS, both in our region and nationally, is currently extremely busy.
"Demand in all areas has risen to levels far in excess of our expectations throughout 2012-13."
It said that it was recruiting extra staff to deal with the demand.