No upgrader happend due to vodacom/cellucity fault and being overcharged r1000 per month for more than 5 months

Good day i upgraded my telephone and data cotract November. When i verified my statement in January i realized that i now pay R1000 more for my data contract. i contacted Cellucity imediately and thy said thy will rectify. now aFTER MORE THAN 20 EMAILS and phone calls i still getting charged at the r1000 higher price it is now more than r5000 i paid for the data contract. the cell conract thy fixed but i also were overpaying for 2 months tere where thy said thy will pay me back for the addition amount charged.