Data *******

I bought a 1 Gig just 4 offer for my tablet.it was a big file that i had to download and did want to use my ordinary data.i started downloading the file at about 02:20 because they said the offer for 1 Gig is between 23:00 and 04:59 for a week.I dont know if it was a technical glitch or did they not specify you will first use your ordinary Data then the promotional data while downloading.But to make a long story short,it used up my remaining data of about 380mb and then started using the promotional data.they state that bundles with shortest validity/earliest expiry may deplete first.***!allthe other promotional bunles that i buy deplete first but not this one.now im stuck with zero data.thanks vodacom