I think then that he must have falsly filled in your details and signed the form instead of you - you can get him charged with fraud I would think and if it was fraudulently obtained, I am sure that you would be able to re-register her and get a certificate with whatever name you wish. Even if you don't want to get him charged, you could use this as ammunition to get his approval to get the certificate changed.
This is the website with all the info you need. Good Luck.
http://www.gro.gov.uk/gro/content/births/regis teringabirth/