Around 4,000 patients will need to register with a new GP after Virgin Healthcare decided not to renew its contract to run two surgeries in Northampton.
The private company - which managed the Kings Heath and Lings Brook practice - has informed NHS England it does not want to extend its contracts for both beyond March 31, 2017.
It means NHS England and the body that commissions healthcare in Northamptonshire, Nene Clinical Commissioning Group (CCG) are now seeking a "caretaker provider" to take care of Kings Heath's registered patients for the next year.
But a letter sent to patients of both practices, has revealed Nene CCG will not be providing a direct replacement for Lings Brook's - meaning some 4,000 patients will need to find a new doctor's.
The letter states: "There is enough space available at the three other GP services located within Weston Favell Health Centre.
"These practices are ready to register you as a patient if you wish."
But there are serious concerns from patients of the Lings Brook practice in particular, who feel the Weston Favell Health Centre will be overburdened.
Joanne Nestor, whose husband Paul attends regularly due to problems with diabetes and cholesterol, says he will now lose vital contact with his diabetic nurse.
She said: "There is an option to stay at Weston Favell Health Centre but, if all patients do this that means that three other practices will have to accommodate over 4,000
patients - this is ludicrous as waiting times for appointments are long enough now let alone with this extra number of patients."
Mrs Nestor, of Ellfield Court, Lings, also fears many people will not be aware the surgery is closing, as the letters - addressed "the householder" - could have been mistaken for junk-mail.
Nene CCG said the reason for the pull-out was because it was unable to "agree terms" with Virgin Healthcare.
A spokeswoman for the CCG, said: “After looking very carefully at all the options for the future of Lings Brook Practice, NHS England and Nene CCG have decided not to look for another provider to offer GP services at the practice.
"This means patients will not be able to receive services at Lings Brook after Friday March 31, 2017, but instead can register at one of the other three GP practices which are located in the same building at Weston Favell Health Centre.
“We had hoped to be able to extend our contract with the current provider of GP services at Lings Brook Practice, Virgin Care, beyond Friday 31 March 2017 but have been unable to agree terms with the provider. These circumstances have meant we have had to act quickly, working with neighbouring practices to make sure local people have uninterrupted access to GP services. Each of the three other GP practices located in the building are happy to accept new patients.
“We will be able to use the space vacated by Lings Brook Practice to improve the range of services offered at the Weston Favell Health Centre and the quality of care that patients receive.
“We have written to all patients registered at Lings Brook to let them know what is happening, and explaining what they need to do next.”
Nene CCG is to host a drop-in information event at Weston Favell Health Centre on Wednesday, March 8, between 3pm and 4pm, for anyone affected by the decision.
A spokesman for Virgin Care said: “Our contract with the NHS to deliver King’s Heath and Lings Brook GP services comes to its planned end on 31 March after many years serving the patients of Northampton and delivering high-quality services. We are now working closely with commissioners to ensure the service can be smoothly transferred to a new provider, ensuring patients are informed about any changes, and continue to have uninterrupted access to GP services in the future.”