I've sorted my glitch out, copying a double-byte send I2C section to create the triple byte I'd overlooked the unwanted I2C_Stop call before sending the 3rd byte, so was never seeing it.

Code:
;======
	call I2C_Start
	call I2C_Address
	movlw 00h		; 00=Command stream.
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 21h		;Column Address;
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 00h		;  Low column.
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 3Fh		;  High column.
	movwf I2C_Command_or_Data
	call I2C_byte
	call I2C_Stop
;
;======
	call I2C_Start
	call I2C_Address
	movlw 00h		; 00=Command stream.
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 22h		;[3] Page Address;
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 00h		;  Start page.
	movwf I2C_Command_or_Data
	call I2C_byte
	movlw 03h		; End page.
	movwf I2C_Command_or_Data
	call I2C_byte
	call I2C_Stop
;
I2C_Start
;-- Start --
	bcf PORTA,SDA		;START commence, 
	call _nops
	bcf PORTA,SCK		;	START complete.
	return
I2C_Address
;-- Address_byte --			;= 78h (bit [0] = R/W. Writing, so = 0.
	bcf PORTA,SDA		;bit 7
	call clk_it		
	bsf PORTA,SDA		;bit 6
	call clk_it		
	bsf PORTA,SDA		;bit 5
	call clk_it
	bsf PORTA,SDA		;bit 4		
	call clk_it	
	bsf PORTA,SDA		;bit 3	
	call clk_it
	bcf PORTA,SDA		;bit 2	
	call clk_it
	bcf PORTA,SDA		;bit 1
	call clk_it
	bcf PORTA,SDA		;bit 0 (R/W bit)
	call clk_it
;	return
;
I2C_Ack
;-- Ack --
	bsf STATUS,RP0	;Page 1.
	bsf TRISA,SDA		;Set as input to release the line
	bcf STATUS,RP0	;Page 0.
	call clk_it
	bsf STATUS,RP0	;Page 1.
	bcf TRISA,SDA		;Set back to output.
	bcf STATUS,RP0	;Page 0.
	return
;
I2C_byte
;-- Command or Data byte --
	movlw 08h		
	movwf countbits	;count the 8 bits RLF
byte_bits
	btfss I2C_Command_or_Data,7
	goto low_bit1
	bsf PORTA,SDA
	goto _clk1
low_bit1
	bcf PORTA,SDA
_clk1	call clk_it
	decfsz countbits,same
	goto _rlf
	goto I2C_Ack ;return
_rlf	rlf I2C_Command_or_Data
	goto byte_bits
;
I2C_Stop
;-- Stop --
	bcf PORTA,SDA		;Before STOP, ensure its low.
	call _nops
	bsf PORTA,SCK		;STOP commence,
	call _nops
	bsf PORTA,SDA		;	STOP completed.
;	call _nops
	call d50mS

	return			;I2C over.