This reminds me of my father, when in the early 80's the Wisconsin Electric co. overcharged us by 24 dollars, and after going back and forth, they insisted they were right.
So he sent them an extra $12.
Then when the bill came back for $12, he sent them $6.
Then $3.
Then $1.50
Then $.75...
Finally someone from WE's accounting dept. called my dad to ask what the hell was going on. And they saw what he was complaining about, and fixed the overcharge and credited the account all within 5 minutes.