Kolkata, Oct 5: West Bengal Chief Minister Mamata Banerjee today raked up the issues of demonetisation and the Goods and Services Tax, dubbing the note ban as the "biggest disaster" and the new tax regime a "great stunt". "As I had said earlier, demonetisation is the biggest disaster. It has completely ruined the country's economy. Also, the GST is a great stunt," she wrote on her Twitter handle. Banerjee had earlier called the GST roll-out as another "epic blunder" of the Centre after the demonetisation. Claiming that the government had "hurriedly" introduced the GST, the chief minister demanded an investigation into the new tax regime. "Why Govt started it hurriedly without making proper plans? The commoners & all traders are the worst sufferers. Thorough investigation is needed," she said.