Matrix Cellular — overcharging

I took a sim for singapore from matrix, i chose the 2999 tariff plan which included india calling free for 500 minutes and 50 gb data, and 500 minutes of free local calls. When i received the bill, it was 12263. They had charged 6830 for india calling, saying i have not used the budget dial. I felt duped since this condition of budget dial was not clearly mentioned. Their agent also did not explain about this.