The 14 week period mentioned on the gov site relates to the time length someone making a new claim should be assessed within to determine if they will qualify for ESA. With things being in such a mess between Atos and DWP, this 14 week time scale has fallen by the wayside, with things taking a heck of a lot longer (months rather than weeks

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With you sending in your form in July of last year, and now receiving the letter advising you that your ESA entitlement will be ending in a few months, it might be worth contacting them to see what it happening iro the form you sent back to them.