ACR DH8 FLC RWY ASSIGNMENT WAS CHANGED 4 TIMES; YET REQUIRED TO EXECUTE A GAR DUE TO DEPARTING AIRBUS. AFTER RESEQUENCING; DH8 FLC CLRED TO LAND ON ANOTHER ASSIGNED RWY. PIC CONCERNED WITH NUMEROUS RWY CHANGE ASSIGNMENTS; ALT XING RESTR; GAR; QUESTIONING WHETHER ATC EVER HAD A PLAN.

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ON INITIAL CONTACT WITH APCH; WE WERE ASSIGNED RWY 25. ON THE DOWNWIND TO RWY 25; APCH CHANGED IT TO RWY 26. AFTER SETTING UP FOR RWY 26 AND SWITCHED TO TWR; TWR CHANGES US BACK TO RWY 25. AGAIN SETTING UP FOR RWY 25 WE NOTICED ACFT CLBING THROUGH OUR APCH PATH ON DEP FROM RWY 17R. AT THIS TIME TWR SWITCHED US (3RD TIME) TO RWY 17R. SETTING UP FOR RWY 17R; WE WERE GIVEN AN ALT RESTR OF 7500 FT FOR ARR TFC TO RWY 26. CROSS RWY 26 CTRLINE; THE REST WAS DELETED AND WE WERE CLRED TO LAND RWY 17R. TWR CLRED AN AIRBUS INTO POS AND HOLD RWY 17R. WE TURNED BASE TO APPROX 4 MI FINAL WHILE AIRBUS WAS STILL ON RWY. WE CONTINUED AND INQUIRED ABOUT ACFT ON RWY. TWR CLRED AIRBUS FOR TKOF. AIRBUS STARTED ROLL AND WE INQUIRED IF WE WERE STILL CLRED TO LAND. TWR LOOKED AT SIT FOR A FEW SECONDS AND THEN REPLIED 'GAR.' WE INITIATED GAR AND STARTED TO CLB; LOSING SIGHT OF AIRBUS DURING CLB. THE AIRBUS REAPPEARED 1/2 - 3/4 MI IN FRONT OF US CLBING RAPIDLY. TWR GAVE US L TURN 140 DEGS AND WE TURNED. WE INQUIRED ABOUT AN ALT; AND TWR ASKED US TO CIRCLE BACK TO RWY 35L. WE LANDED ON RWY 35L WITHOUT FURTHER INCIDENCE. OPERATIONAL PROBS: MULTIPLE RWY CHANGES FROM ATC. APPARENT LACK OF PLANNING BY ATC. INCREASED WORKLOAD ON CREW BY ATC. ATC'S FORGETFULNESS OF ACFT ON RWY. TWR CLRING ACFT FOR TKOF TOO LATE; CAUSING THE GAR. FEELING BOXED IN ON GAR BY DEPARTING ACFT IN FRONT AND ARR ACFT (BEHIND). UNCERTAIN ABOUT WHERE TO GO AND TO WHAT ALT TO CLB ON GAR.