Name adding on birth certificate

I app**** to add a name onto my daughters birth certificate, when doing so I was told that it will take not more than 3 months, I then went to the branch I app**** at 3 months later only to be told that I should call the call centre for feedback. I did that today which is over 6 months now, I am told it will take over a year to do so. I have things to do & I am not happy because the information I was given at the beginning was wrong, why does it take so to add a name, when applying for an ID or Passport is minimal.