<prompt> Human: So awhile back i purchased a sound system on credit like a moron. I could afford payments on it no problem and the store was running a no interest in 12 months if paid in full promotion... The issueing credit bank was ge now synchrony. I set up an auto pay account and never really looked at it after that. I got curious about where I was at with that account today and decided to log in and look into it. Turns out my balance last month was 154 and this month it increased by around 800! Woah. Turns out my defered interest promo period was up and I had no idea. The worst part is that the cycle ended two days ago and i could have paid it off then no problem. Is there anything I can really do? If i call is there any argument I can make beside my own stupidity and oversight? Thanks for your help... UPDATE: I just called synchronay. They waived all the interest since I told them I would pay off my previous balance right now. This was a good lesson for me that could have turned out much worse then it did. I will be sure to monitor my accounts more closely in the future. Also for anyone else that finds them self in a similar situation, remember, it never hurts to ask the bank. The employees are people too and can be sympathetic. Thank you all!  <response>: I used to work for a furniture store that offered 0 financingthrough GE at the time, and the companies setting up these 0 interest promos with deferred interest intentionally set up the minimum payments such that the amount will not be paid off during the 0 interest period. Im sure even though we made the extra effort to warn our customers of this, and help them work out their actual minimum payments to pay no interest, that a large of them still got caught by it.The finance company is not going to let you off, they got exactly what they were hoping for. 