Last in - First Out - Nonsense

Hi Vodacom. I would just like to find out why your policy is not to benefit the customer but to benefit yourself? I bought data last month, for which I still have 1 gig which will expire on the 12th December. On the first of this month, i received 2 gigs of data which will expire on the 1st February. Instead of using the 1 gig that will expire this month, you are subtracting my usage from the data that will expire in February. Does that make sense? So the 1 gig that i paid for will now expire before i even use it. Guess this way you make the money