I bought an s8 3 weeks ago. I asked the sales clerk if I should wait because the s9 was coming out and I thought the s8 would go on sale. he assured me it takes months after a new phone launch for the older model to reduce in price. trusting him I purchased my s8 for $590 on a tab med. The price now, only 3 weeks later, is $200. can I get a refund for the difference?