I applied to the KC to add my new affix to my existing bitch but they won't let me do it. They said that her name had been changed by her previous owner (but I've had her since she was a babe). Is there any way I can get round this? I'd like her to have my affix (at the end of her name obviously). Any thoughts?

If no previous owner has changed her name and she has not got her stud book number then you should not have a problem. 

But the KC say they have. How do I find out? And what diffenrence does it make? 

You would need to see the Breed Record Supplement to trace what has happened, if the "breeder" has not told you. The puppy might have been registered (and actually bred by) someone else, a close relative or friend of your breeder?. Your "breeder" may have then transferred it to themselves and added their affix, before you purchased it. I would have hoped that they would have told you about this beforehand though? Some people do this to avoid registering too many litters in a year, but there may be other reasond too?

Kay

like kay says, go back to your breeder, is there not already an afix on the end of her name?  mayube you could phone up the KC and ask for details about it all?