price increase but prices weren't change of shelf only in da system

hi I went to game west street yesterday bought Polaroid earphones which was 189.00 on their shelves,while iwas paying didn't check how much they took,arrived home check my till slip wow they charge me 399 ,den 2dae went there went to customer service they help me nd gave me money back,because ineed the earfones went and ask another girl upstairs and ask can she check the price for the Polaroid earphones she took then and check dem and on their systems its 399 but on da shelf it 189 ask her y is dat she said she don't knw I ended up buying amplify earphones for 249 of which I didn't want dem, y y y don't u change prices on your shelf