In the Court of Appeal today, he told the judges Wickliffe instructed him to "shut up and just let her do her job".
He claimed he also didn't know about the alibi being submitted to court for his defence.
"My partner went and did that behind my back, and gave that alibi evidence behind my back. I found out about that later on," Austin said.
Austin claimed he wanted to give evidence during the trial, to tell his side of the story, but was pressured not to take the stand.
Wickliffe presented a sworn affidavit and gave evidence to the Court of Appeal that it was Austin who said he wasn't there when the crime was committed.
She said she had talked to him about the evidence he was there, and how it undermined his case. But he had repeatedly told her he wasn't there.
"We went through the cell phone data and it wasn't active during that period.
"And he said to me, if my wife wasn't texting me like crazy, I must have been with her. Because she was very possessive, according to him."
Wickliffe said she had told him she could still defend him if he had been in the area when the attack happened, but he still told her he wasn't nearby.
She admitted warning him against taking the stand in court, but said that was because of his "highly agitated" state.
"After the way he had conducted himself in the courtroom I was concerned about him giving evidence.
"I talked to him in almost every adjournment because of the way he was conducting himself, the battles I was having with security, and his focus on his partner.
"I've set it out in my affidavit and I'll say it again. From the moment he sat down in the dock and his partner sat behind him, he was talking to her, whispering to her.
"Security was having to tell him to face the front. I can barely remember him facing the front the whole time.
"His whole focus was on connecting with Abby, and that went on the whole trial.
"Never once did he say he wasn't happy with the way I was conducting the trial."
She said she first saw the letter changing his story about what happened on the night of the attack when she received a copy at the same time as police and probation.
The Court of Appeal has reserved its decision.
Shaun David Austin, 37, and Robert Eric Austin, 40, were sentenced last year in the Auckland District Court for savagely beating two men who were fishing at the Ti Point Wharf on April 1, 2015.
The Korean men, both Auckland-based pharmacists, had driven their new car to one of their favourite spots for some night fishing.
In the trial, the Austin brothers were found to have attacked the men at night, with Shaun Austin demanding car keys and wallets, while he held an axe.
When the man refused, Shaun dragged him from his car and began punching and kicking his head.
After several hits, Shaun used the axe and delivered a sickening strike to the man's head, with the back of the weapon.
The court was told Shaun then uttered to his brother, "let's finish 'em off", but Robert insisted they flee the scene.
The two men survived but told the court last year they suffered ongoing medical problems, and no longer returned to their previous favourite fishing spot.
