Data Theft - Consumer Complaint for Vodacom - Head Office

Why don't Vodacom first use up the existing data bundle that I have. They send me an sms saying yr data is low,so I recharge. Then they immediately start using the new bundle and what is left on the old bundle expires(which they kindly tell me a week before it expires) and I have no way of choosing which bundle to use' first. They are thieves. Very simple. Enriching themselves at the cost of the public who don't have contracts.Thieves.!