After a banking mishap, Mark Hunt went head-to-head with Westpac Australia, who didn't stand a chance.

UFC fighter Mark Hunt has just won the most satisfying fight of his career after taking on Westpac bank over unfair bank fees.

The mixed martial arts star was disgusted to learn he had lost more than $20,000 when the bank closed an account unexpectedly.

After giving Westpac a piece of his mind over the telephone, he also took to Twitter to express his anger, with many of the tweets too explicit to print.

Hunt said Westpac returned the money "just because I abused the hell out of them" he said.

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Hunt, who reportedly earns $350,000 per fight, is warning others to keep a close eye on their accounts in case banks try to charge them unnecessary fees.

"I can't believe they would do that, I've been a customer for so long now, years and years," he said.

"It's not fair, you just can't do that to normal people."

It all started with a loan that Hunt took out to purchase a Sydney gym. He paid the loan back more than a year ago - but a 9 per cent interest rate was still getting charged to the empty account.

This put the account to arrears of around $400, adding another interest fee for the arrears on top the loan interest, which he was not happy about.

Although disgruntled, he paid the money to pull the account out of arrears anyway, hoping that would be the end of it.

Next, he said he put $20,000 in to the account, "just to see what would happen".

The account balance steadily decreased he said, and next time he checked it, there was only $19,000 in there.

Then the account disappeared.

"They didn't notify me about anything and then when I went to go transfer some money, I couldn't do it."

He said Westpac Australia had closed his account, without notifying him and for no apparent reason, he said.

They didn't have a proper explanation for the fees which were being charged and kept back tracking on their excuses he said.

"They just kept charging me and charging me. They said you're supposed to close (the account) yourself but they never told me that."

Hunt said he was then told it was because the account was on arrears from interest on his loan - which he had paid back - so gave them an ear bashing over the phone.

A spokesperson for Westpac Australia said they cannot comment on personal bank accounts for privacy and confidentiality reasons.

"We take complaints very seriously and we work with customers to resolve satisfactorily any issues that they have with their banking."

Banking Ombudsman Nicola Sladden said banks were under no obligation to do business an individual, however, they should not close an account without good reason or giving the customer reasonable notice.

Sladden said if customers were not happy with a bank's response to their complaint, they should contact the Banking Ombudsman's office.

* Have you had a bad experience with your bank? Email news@star-times.co.nz