I raised an equality complaint against my employer 4 months ago and have yet to receive a response.  My employer does not provide updates on progress in except when I chase, and those updates are vague and state that they hope to complete their investigations soon but cannot commit to a date.  They also say that the investigator only works part time which is contributing to the delay.

This is a prominent public sector regulatory body employing 3000 people.  

Is this reasonable?