I just tried my "unflavoured" whey protein from MyProtein and it tastes of vanilla. Completely different to the last two batches I had. Quite annoying as the vanilla taste is really fake and disgusting when it repeats on you :/
Did you not use flavouring?
I suggest you buy some liquid flavouring from MyProtein.
Try toffee. Thats the best flavour I've tried. It costs about £3.99 + delivery.