Disappointed

I have a problem with vodacom i toke black friday deal November and i was paying R1239.32 gor all my contract all along and December they debit R1378.69 and i was suprice why they debit that mkney instead of R1239.32. 4 December i received my black friday deal for 2TB bytes data and they give me 2TB for December and i didn't use my data at all i was away January i expected to receive another 2TB when i check my data still is 2TB means they didn't topup data but they double charge me for December and January for that home router of which i received data for December and i didnt receive any data January