Withholds consultant's refund money for two years

I made a double payment on my account as a consultant. After much ado, I finally manage to send all the documents they request including a ridiculous request for a signed letter confirming I want my own money refunded to me. Then they respond saying I still have documents outstanding. When I refer them to other emails, they say I must send all the attachments in one email. The money they owe me has now decreased in value because of inflation, and all the while they are stalling, they are collecting interest on it. They also insist on sensing ridiculous emails instead of calling. When we must pay the account, I'm sure they take the trouble to call. But won't be bothered to call when they are the ones owing money. I am willing to bet they plan on responding to this review also with a generic script, followed by an empty, platitudinous email, to continue stalling and not process the refund, even though they have all the documents and there is no reason to deny my refund.