Desirous of change:
There are specific instructions that the written files of the Judicial Committee concerning a matter of DFing are to be collected by the JC Chairman, placed in sealed envelope with only individual name on the outside and date and it is to be maintained in the Cong Confidential Files indefinitely if the person is not reinstated. Supposedly they are destroyed after reinstatement, after all restrictions are lifted, and after publisher is in good standing for 3 or 5 years (don't recall specifically). However, most Cong Secretarys are too lazy or stupid or apathetic to bother.
You can "request" anything. Don't expect to get the answer you want to hear.
I don't know whether this happens in the UK, but the only basis they would have for keeping anyone's personal information would either be explicit permission (I remember in the distant past we all had to sign something to say it was ok for them to keep our records) or on the basis that we are members of the religion and have regular contact. If anyone ceases to be a member (i.e. D/F's or D/Ad) there is no legal basis for keeping the records. They must destroy the files if the individual requests it (i.e. withdraws their permission and ceases to be a member) or risk getting a fine of up to £500k for each breach of the data protection act from the information commissioner.
I don't know the legal basis in the US but I should imagine there must be similar legislation