[imnukensc]

Other than the yellow legs, doesn't look anything at all like a leghorn to me.

 

[imnukensc]

Looks like a mix to me, too, but I don't know of what. Seller should know, but they apparently already told you it was a leghorn which is totally incorrect.

 

[imnukensc]

After some Google digging, I guess it could be a rose comb leghorn. I am not familiar with that breed.

 

[imnukensc]

Talking about the first bird. I can't see the comb well enough to say if it's rose or single. I wish the OP had been a little clearer about rose comb leghorn vs just calling it a leghorn. I still don't know that it is a rose comb leghorn, but if it's like the other pics from the seller, then I suspect that it is. Again, I'm not familiar with the breed.