Vodacom recants on offer

I have been a Vodacom customer for over 10 years.<br> Last week I received a telephone call from Vodacom making me an offer as \a valued client\" for an additional service which I accepted.<br> Shortly after ending the call I received a SMS stating that my application for an additional line had been declined.<br> As this was an unsolicited offer made by Vodacom, how can they decline?<br> After calling Vodacom I was informed that the offer was made by one of their agents and that they are therefore no obliged to honour the offer.<br> What utter *******!!!"