help please

[terrence]

hello, hoping someone can help!
I'm trying to register as a british citizen through my british born mother.
I sent all of the information off about 5 weeks ago and yesterday recieved a letter from the ukba.
My surname is my stepfathers and that is what I have used since I was 10 but there has never been any legal steps taken to change it.
My birth certificate that I submitted was my real fathers surname but my birth certificate is the only legal document that has this name.
they are asking for me to provide proof of this name change ( 1989- 10 years old) but I dont know what I can provide to satisfy them.
They are also asking for my current passport but the only passport i've ever had was an American one that expired in 1994.
This passport has since been lost during a house move.
I have not travelled since then.
I cannot find a contact telephone number for the ukba and they only send me a FAQ form when I try to e-mail them.
If anyone can help I would be greatly appreciative
Thanks.

[madhumesh]

This is ukba general contact details if you have not looked at it already.