Vodacom data

Recently upgraded my cellphone contract again through Vodacom. Received 5gigs of data with the upgrade as I always have in the past. Today 7 days on I woke up with an sms from Vodacom saying that you have no more data. Didn't seem right as I didn't use much of it. Phoned customer care and it was explained that the data was only a promotion for 7 days. So my problem is two things, why was I never told that the data was only for 7 days as I was in the vodashop for close to two hours, surely if it is a "promotion" like they call it then it must be promoted to me, the customer. Then secondly, how is it fair to charge the customer hundreds of rands to upgrade and then only give them data for 7 days when it has in the past not been like this. I have been a loyal customer of vodacom for close to 20 years and this does not seem like a fair deal to me. I think the data should be given to the customers to use when they wish to as it was in the past.