CONFUSION; DISTRACTION WITH FMS ANOMALIES AND FAILURE TO COMMUNICATE CAUSE AIRBUS FLT CREW TO COMPETE FOR CONTROL OF THE ACFT DURING A GAR.

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ON APCH INTO ZZZ RWY XXR; TURNING DOWNWIND ON THE STAR; THE FMS DUMPED OUR FLT PLAN. WE WERE VFR SO WE CONTINUED THE APCH ON ATC VECTORS. I HARD TUNED THE RWY XXR ILS INTO THE 'RAD/NAV' ON THE FMS. ON FINAL; MY FLT DIRECTOR DID NOT AGREE WITH THE ILS GS; SO I CALLED TO TURN OFF FLT DIRECTORS. WE DID NOT GET SWITCHED OVER TO THE TWR; THEREFORE; WE DID NOT GET A LNDG CLRNC. SO WE DID A GAR. ON THE GAR WE HAD TO FIND THE CORRECT RADIO FREQ AND THEN GET A HDG AND ALT TO FLY. I BELIEVE IT WAS 360 DEGS AND 3000 FT. WE WERE ALSO CLEANING UP THE ACFT AS WE CLBED TO 3000 FT. I STARTED TO LEVEL AT 3000 FT BUT THE ACFT DID NOT SEEM TO WANT TO STAY LEVEL AT 3000 FT. IT TURNS OUT; ATC HAD GIVEN US 5000 FT AND THE CAPT WAS TRYING TO CLB THE PLANE UP TO 5000 FT AND I WAS TRYING TO LEVEL OFF AT 3000 FT -- CANCELING OUT EACH OTHER'S INPUTS. I THOUGHT I HAD A CTL PROB AND ASKED THE CAPT TO DECLARE AN EMER. HE DID. I REALIZED THE CAPT WAS TOUCHING THE CTLS AND ASKED HIM TO STOP SO I COULD GET CTL OF THE AIRPLANE. HE DID. THE CAPT THEN PUT MY FLT DIRECTOR ON AND ALSO TURNED THE AUTOPLT ON. WE CLBED TO 5000 FT. GOT VECTOR TO FINAL; RAN THE CHKLIST; AND FLEW ANOTHER ILS XXR INTO ZZZ FOR LNDG. I DON'T EVEN KNOW WHAT CORRECTIVE ACTION SHOULD BE TAKEN. THIS SHOULD NOT HAPPEN; EVER. ONE PERSON FLIES; THE OTHER DOES NOT.