As you can see from my earlier post, i had the same problem with Tesco, i wrote to them quoting section 2 of the credit agreement on interest free periods; they changed my statement to reflect the full period.

From the letter they sent to me, i discovered that the agreement should  be worded "upto 12 months interest free period". which is suppose to give them a legal right to minimize the free period as they wish.

MY ADVISE: read the agreement if it says "upto" then you won't get the full interest free period.