How to charge for the second article of Jiangxi Mobile Broadband?

30 yuan every month. The mobile sub-band of Jiangxi Mobile Broadband refers to the second broadband with the same number, which needs extra charge. According to the monthly 30 yuan, there are also preferential activities. Broadband account manager launches monthly return activities of 30 yuan broadband TV package for target users. After converting the returned phone bill, the second broadband is equivalent to free during the activity.