Subject access request

Can someone tell me can I do a subject access request to Capita to find out more information as to how they dealt with my complaint to them or should I just wait until I have submitted my complaint to the Independent Case Examiner.  Also should I do the same to the DWP or leave it to the Tribunal.

I am not going to ICE about the DWP it is about Capita.  They have not given me a proper explanation about the assessment that took place so I want to take it further. I would have done it by now but I have had a few bad days. The SAR was only an idea.  I have applied for SARs in the past with other organisations & they proved to be quite useful.

I have been through the Capita complaints procedure.  In the last part of their second & final letter  they say "if you are not satisfied with this response you can refer your complaint to THE INDEPENDENT CASE EXAMINER using the following methods.  The letter then describes the various ways you can contact them.  I have also been on the ICE website to find out what to do.  I will be preparing a letter and sending it off during the next few days.  I know what I am doing.