Send the BOE a letter saying you are no longer a member of such and such congregation and are looking for another more Christian and welcoming JW congregation. Although in no way is your decision to withdraw membership from that Congregation in particular to be interpreted as disassociating with the whole association of JW's. Only you wish to stop the maligning and damaging relationship the local BOE has develop with you and want to seek a more peaceful and beneficial congregation for you.
The next day send them another letter saying that if they dare hold any religious based judicial proceedings against you or in retaliation for your decision you will depend on legal counsel to bring them to court as a BOE for their not following their own rules published in WTS publications.
Say that you will not sue the WTS or the traveling representative unless they become actively supportive of the BOE's past harrassment and mistreatment of you as a congregation member.
The BOE will get a black eye from the CO and the Branch because they don't want to be involved and your relationship with the BOE could cost them legal troubles and bad publicity.
They will stop hounding you.
Take your time. Maybe you'll find another JW Congregation to be a member of, maybe not ever, but whatever the case it's your decision to be part of it or not.