Well......for a start maguras are much much better then V-ees when bled properly and have the right booster and pads!!
Well it either sounds like frame flex, pads not set up square to the rim or a rubbish bleed!
Your best bet is to see if you can find a bleed kit off a mate or ask to borrow a local bike shops if they'll let you and bleed it!
Also make sure when you bleed it the TPA is in, I think its in anyway, well just sit on the bike and screw it till it goes all loose and feels like its full of air.
Make sure the pads are set up square to the rim as well cus if there at an angle the pad will compress and make it all spongy!
Rob (Y)