Hi, I asked this question already, apologies, just was hoping it hadn't got 'missed' as I also asked another question in a different post that was answered (thank you

).
Yesterday my CPN telephoned to tell me my PIP decision after my latest review. It has stayed the same thankfully but the award length is for 18 - 24 months - again! My CPN argued my case for a longer award (with unstable bipolar I regularly have debilitating episodes despite meds which, by very nature of the illness, will not 'get better') but the DWP decision maker was adamant. She said her hands were tied, the rules had changed and that all cases now are getting 18 - 24 month awards, no-one is getting more.
I can't believe that is so? I have now done 3 forms in 3 years and it is stressful already knowing that it will come around so fast again.
Is it right? Can I appeal it?