The good- not so good customer

My wife cancelled her laptop in April 2018, the lady at the cancellation department said to her she is a very good customer,and offer her a wifi router and 10 gb anytime and10 gb nightowl for R139 a month. We received the router and found out that we are billed R129 for 5gb anytime and 5 gb nightowl, that is not what we have agreed to. We phone them,they will look into it,today a week had past,nothing from Vodacom!!!