Q: Still vibrating after new tires, re-alignment, and balancing when I go over 70 mph

Car vibrated when I'd go over 70mph and I'd hear a "whomp whomp" sound from back and it'd pull to one side. First had a rebalance and re-alignment. Vibrated less but still heard noise. Took it back, they said back tires were feathered so they replaced them with new tires but put them on the front and old front tires on the back (were still good). Sound is gone but still vibrates on highway. Took it back, re-checked tires, said they all looked good but weight had fallen off the front tires. So they rebalanced them AGAIN. Car still vibrated but now I feel vibrations in my seat and a bit in the steering wheel and then noticed I hear a "knocking" noise when I turn right (Wasn't there before). New mechanic at Kia said it was a weight making the noise. They fixed it but car STILL vibrates. WHAT COULD BE THE PROBLEM. PLEASE HELP!

My car has 23000 miles.