ESA SDP not added to benefit.

Hi all again, I asked earlier about ESA and carers allowance and what the effect would be to my ESA premiums, it now transpires that I have not been awarded the SDP only the EDP, I am on high rate DLA care and low rate Mobility. I understand that I need to claim this premium with a form ES10 ? Can anyone shed any light on this please, I am long term disabled and would have thought this would be added automatically, if not I have lost a huge chunk of money over the past 5 years. Many thanks.....Paul