The spiralling population of Bicester has forced Post Office chiefs to give the town three new postcodes.
Businesses and residents currently share the OX6 code but from September it will be replaced by three new codes OX25, OX26 and OX27.
Mail users have been reassured that the OX6 code will still be accepted on letters for another year but one angry resident says not enough warning has been given.
Derek Padley, who recently moved into Lucerne Avenue on the new Bure Park estate, said: "This is quite major. I have just moved into a new house and I was told the one postcode - now it has changed to another one already."
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