Complex sentence: Prior to September 2014, Club Sobeys/Club Thrifty Foods was also available in Western Canada, and are currently in the process of transitioning to Air Miles after Sobeys' acquisition of Safeway.
Split into simpler sentences: Prior to September 2014, Club Sobeys/Club Thrifty Foods was also available in Western Canada. Those stores are transitioning to Air Miles after Sobeys' acquisition of Safeway.