Just tell them the prob's you've been experincing, as to the balance it depends on the wheels you have. The near to perfect balance is to have bang on weights in and outside the wheel, next best is what is kniwn as ali 3 (band on on inside and sticky behind the spokes, and last is ali 2 which is stick on weights as near to the inside edge of alloy as poss and sticky weights behind the spokes. Also ask them to make sure they get the balance as near to zero as poss. Most machines have a fine button which tells the fitter how close to zero the wheel is. As I said before mate go to Costco and get them to do it. As to D.K he's normally just round the corner to my work at his 2nd home AmDEssex