Prices can never go back up? Is that even possible? Discounts have to be based on discounts?
You are not allowed to advertise something as being on sale for a set price for an extended period of time, after a while it must just be advertised as the price, even if below MSRP. If you then want to advertise for example a 50% sale, you must discount the 50% from the price it has been, you cannot raise the price back to MSRP and discount 50% from that, as it is misleading the consumer into believing they getting a bigger discount than they really are.
I don't believe what Sony has done is illegal, as it is 'buy one get one free' which is not misleading. But it's certainly immoral and skirting the law.