ESA help

Hi

While I am waiting for PIP I need a question answered about ESA.

I claimed for contribution based ESA in 2011 and got straight into the support and was told I would be reassessed in 12 months, so in 2012 they sent the forms out and we filled them in and never heard anything so I called them and was told I was still in the support group and was told I would be reassessed in 24 months, I did mention at the time that I thought it was stupid to keep reassessing me in a short space of time as I know all reports have said I was never going to get better, but that was the last I heard from them. I have not had another letter for reassessment and they keep paying me and I have never been told I am on this benefit and won't ever be reassessed. I have CP that effects my left side and I need a right elbow replacement (it is deformed and looks like I have 2 elbows on one arm) which will never be done due to complications, so my question is do I call them to ask why haven't I been asked to be reassessed or am I one of those people who have now been granted life on ESA? it is worrying me and if they ever felt I can work then I am in trouble financially, we knew my mobility was going down hill and I would end up in a wheelchair which is now happening but never thought my elbow would give out and would have to give up work altogether. Any advise would be appreciated.