new aggrieved buyer here~!

last time i bought a PQI 512MB trumbdrive at Sri Comp. But after using for half year, the size of thumbdrive drop down become 256MB only~!!
i m dun mind on whos fault, but at least still got warranty. Then i take back to warranty, the Sri Comp technical always break his promise.....say change 1 to 1 new thumbdrive to me. But always say no stock.....i already drive car go lowyat for 5 times above.....the petrol money and parking fees can let me buy another new thumbdrive de~!!!
U all must say, i should call for confrim whether got already or not before i go lowyat. But the technical always just say, the stock will be come at what day, what day......blar blar....so i just trust him one time and one time~

no buy any thing from Sri Comp again~ again~