I've mentioned before that my mate owns/runs a Tyre & Exhaust place with his family.
When I've been down there I have seen the Younger lads balance a wheel up & stick a crap load of lead on it to balance it, My mate or one of the older dudes comes along Laughs sticks it back on the machine, Busts off all the weights & balances it with a quarter of the lead.

I don't know what they do different but I do know there are two ways to achieve a Balanced wheel/tyre. One takes a Crap load of lead & one don't.
Take it back & get one of the more experienced Dudes to balance them again.