Hi Helen, sorry to hear this.
Your ESA is contribution based (on your N.I. contributions) rather than income based. It used to be payable indefintely, provided you continued to satisfy the medical requirement, but sadly that is changing w.e.f. April, when it will be limited to 12 months and this will be applied retrospectively.
I've had pretty much the same thing recently. I lost my tribunal hearing over the withdrawal of my ESA following the Atos medical assessment, so I applied for JSA. This claim was refused under the new rules on the basis that I'd already had more than 12 months ESA.
This leaves me in an extremely precarious financial situation and I fear that many more are doomed to suffer the same fate. My hatred for Cameron and his fellow bunch of Tory crooks has no bounds. I wish them all a slow and painful death and soon!