Why is Vodacom unable to cancel a phone number???

I have been trying to cancel a secondary number which is attached to my main account for SIX MONTHS. It has data bundles that have been activated on it (which I have not done) and I have paid thousands into this number. Every time I speak to the Cancellations department, they can't cancel the number because there's an 'open order' on the line which no one there seems to be able to close.. whatever that means. I've now tried to de-activate the data bundles - and guess what - I can't! Every time it is 'escalated' to management, I hear nothing back. I am absolutely flabberghasted at why Vodacom cannot do something which should be an absolutely normal process for them. I am a very, very unhappy customer.