mine did exactly the same, cheap plastic that came of the end. i do totally regret buying cheap, but you learn the hard way dont you tbh. i can only afford to replace 2 right now, but the plan is to def replace the lot and get dpn's the same as i love bamboo.
i ahvent knitted with anything other than plastic (hate those with a passion, they breat on me left right and centre, i only have 1 compete set left now, oops lol) metal, aluminium and now bamboo. i did get some free 15mm wooden once in a mag that were ok though. think id get on with anything tahts not metal. it gets to hot here in the summer to knit with metal, the yarn dosent slide at all.
i know this time i'm buying 1 then trying before i buy the lot, not going that route again. i think i paid £20 inc p&p for the last set, that was 15 bamboo circ's. they knitted great, very comfortable etc, just flipping broke. and yes i did swear now i have had to put a jumper down that im not that far of done with. i'm having to put a scarf down now as well as the needles look a bit ropey as well. they would be there as a back up if i dont kill them now lol
i'll have a look where i can buy harmony once i think in europe.