Magnify On Lazada.sg review: price of dyson hair dryer dropped drastically within 1 week

I shopped on lazada. Sg less than 1 week ago 30th aug 2017, bought a dyson hairdryer without brown box through vendor magnify on lazada. Sg and today 6th sept 2017 when I checked the hairdryer price online, the price dropped drastically from sgd$598 to sgd$499 through the same vendor magnify. Kindly revert me with explaination and I would like a refund for the difference please. Thank you.