Phobic avoidance of traumatic contents (of the mind) is the cornerstone of dissociative disorders. They are basically constructed out of the need to avoid the trauma!

In my therapy we have had protectors that have refused to let us get close to the traumatized parts. My T has been using Family systems therapy and adapted EMDR techniques to work with those parts in an attempt to find out how and why they need to protect us. Every time we do it we successfully work with another level of protectors and get more access to the traumatic memories. Once we are able to communicate with them more effectively their reason for "refusal of entry" is very easily solved.

If you try googling "phobic avoidance in dissociation" and "family systems therapy protectors" you might find some interesting books or articles.

I wanted to add the reasons for preventing us from accessing the trauma stuff are usually based around our protection, even when initially it doesn't seem that way. We have protectors who just shut everything down (like turning the lights off, nothing can be seen) and others who are aggressive bullies who attack us internally if we get too close to something. Both kinds of protectors, who seemed to us to be very powerful, large, looming an terrifying, turned out to be children. Scared children.

All is not always as it first appears.
Approach them with love!