Code:
$ awk '/^X/ { S=$0 ; getline ; $0=S $0 } 1' inputfile
A10
Records of transfer
File received
P195,P195,P15,
C195,C195,C15,
X,X,X,X,1,1,1,0,A.10,B.10,C.10,D.10,E.10,
F.10
X,X,X,X,1,1,1,0,A.11,B.11,C.11,D.11,E.11,
F.11
X,X,X,X,1,1,1,0,A.12,B.13,C.14,D.14,E.14,
F.14