Very Poor Customer Service

I'm very disappointed with the service rendered by Vodacom. I app**** for the cellphone contract via iStore Eats Rand Mall and was assisted by Zinhle. Whom I'm also not unhappy with her service. Application was successful and was told come back the following day because they needed to confirm with the iStore head office before they could issue the phone. So when I got home I released that Vodacom had a 2 for 1 mother's day special. So I was interested in that so I went to go cancel my contract and advised Zinhle, it wasn't a problem I was advised to sign cancellation letter of which I did and told it'll take 5 working days. The 5 working days was on the 31st May and the excuse I get from Zinhle is that Vodacom staff don't want to do they work. All they giving her is excuses that I need to be in store for the cancellation. So I've asked Zinhle to send me the names and references of the people assisting her with the cancellation and she hasn't responded to me with the names so I can take it up with Vodacom..... Please kindly give feedback ASAP because the 2 for 1 deal mother's day deal is ending tomorrow.