A coalition of residents' associations has written to Health Secretary Jeremy Hunt to urge him to intervene amid claims Purley War Memorial Hospital's downgraded urgent care centre could be closed altogether.
Eight groups, representing neighbourhoods in Coulsdon, Purley, Kenley and Sanderstead, united this week to step up their opposition to changes they fear will culminate in the loss of the service.
Croydon Clinical Commissioning Group (CCG) halved the Brighton Road GP-led unit's opening hours last year, from 12 to six a day, just months after the hospital reopened following a £11.5m refurbishment.
Campaigners claim the department was downgraded from an urgent care centre, which treats urgent but non-serious health complaints, to a minor injuries unit without proper consultation.
They fear it foreshadows the complete closure of the unit, which is now open from 2pm to 8pm each day instead of opening at 8am.
They wrote: "The CCG have repeatedly denied there was a downgrade, have been intransigent in our discussions, and have suggested that further cuts in services may be forthcoming.
"They have indicated that a full closure of the urgent care centre is an option being considered, with more services being centralised at Croydon University Hospital (CUH).
"We therefore ask you to intervene in this matter to ensure that our residents get the local urgent care service they need, as originally agreed and implemented."
The letter is signed by members of the residents' associations for Coulsdon West, East Coulsdon, Hartley and District, Kenley and District, Old Coulsdon, Purley and Woodcote, Riddlesdown and Sanderstead.
The areas have an older average demographic than elsewhere in Croydon, making public transport to CUH "impractical for many", the groups said.
The letter added: "In our meetings with the CCG they have indicated that a full closure of the urgent care centre is an option being considered, with more services being centralised at Croydon University Hospital.
"This completely disregards the need for local provision of services for our residents and ignores the travel difficulties they face in getting to CUH."
Paula Swann, chief officer at the CCG, said analysis had showed there was "very limited demand" for the service in the morning.
Croydon South MP Chris Philp talks to campaigners outside the hospital on Friday
She said: "The nurse-led minor injuries service at Purley War Memorial Hospital did not deliver high quality, safe services in line with national guidance and best practice in urgent care. Neither did it deliver value for money."
She added: "We removed the minor illness/ailments element as these conditions can be managed at home, or with the help of a local pharmacist or GP rather than in a hospital setting.
"Local people have told us they are supportive of our plans to deliver the right care at the right time and to reduce the reliance on urgent care services for minor illnesses."
The CCG is currently carrying out a review of urgent care across Croydon, with closure of the Purley minor injuries unit one option under consideration.
Croydon South MP Chris Philp said he would lobby for the 12-hour service to be restored instead.
He said: "They should never have downgraded the service in the first place. The use of that service was growing very rapidly and it was a very valuable service."
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