Did you actually buy a blackberry plain, or just top up your credit balance?
Dial *100# for credit balance
Dial *100*7# for goodybag minutes allowance and expiry date.
Have a look at your "order history" and see what is displayed. Date,content,amount and payment status. See here - https://giffgaff.com/orders/history
Here's a guide about how to buy a goodybag / blackberry plan from airtime credit - http://bit.ly/kbggbagfromcredit