1999 Volkswagen Polo wheel bearings?

I have had a lot of problems with my bearings, I have had to get them fixed three times in the last 9 months (front bearings in particular). This last time, afterwards teh steering wheel was off and the wheels have been wearing down on the inside. I took it to the garage (AGAIN) and he told me that the flange has a notch in it which means the bearings will keep going. He says he has to replace the wheel hubs on the front and I'm looking at £140 per wheel. Is this right? does any of this make sense to anyone? Because I am proper skint, he said there's not point picking up wheel hubs from the scrap yard as they'll probably have the same problem. He said it's expensive as he's ordering them from VW. Could someone just let me know if this is right or if I can save some money somewhere???! (The bearing are still under warranty)