Complex sentence: Shahrdari was relegated at the end of the 2011--12 season, they were promoted back to the Persian Gulf Pro League the following year but were relegated to the 2nd Division because of a match-fixing scandal.
Split into simpler sentences: Shahrdari was relegated at the end of the 2011--12 season. They won promotion back to the Persian Gulf Cup the following year but were relegated to the 2nd Division because of a match-fixing scandal.