Complex sentence: Until 1 October 2002, each retailer supplied gas in a defined geographical area, and from that date the gas market in Victoria was opened to new gas retailers and full retail contestability for gas customers was introduced, enabling gas retailers to seek customers state-wide.
Split into simpler sentences: Until 1 October 2002, each retailer supplied gas in a specified geographical area. On 1 October 2002, the gas market in Victoria was opened to new gas retailers and full retail contestability for gas customers was introduced, enabling gas retailers to seek customers state-wide.