Sears no interest plans on credit cards

Last December, I bought at sears a washing machine, using their 12 months no interest plan. What they do not tell you is this, You have a balance on the account? I set up my payments to cover what my old balance was, and , now 10 months later, I find that none of this went against this purchase. They always do this last unless you call them when you make a payment to tell them what to put it against. Where is the truth in lending? or does it not count in credit cards? don't buy from sears, or use citibank for anything. They will always find a way to rip you off