"Many contracts failed to accurately disclose payment details including the total number and amount of payments and the date of the first payment. In total, at least eight items of required information were either missing or inaccurate."
Budget Warehouse's contract documents also misled customers about delivery guarantees and what its liability was for loss or damages caused by the products it sold.
Best Buy, which operated in Auckland and other North Island towns, was fined about $83,400 when it was sentenced in Auckland District Court last Thursday.
It had earlier pleaded guilty to 16 charges under the CCCF Act relating to its credit contracts, which were unclear and left out important information, the commission said.
It was further ordered to return $37,180 to customers.
The company used two different contracts between June 6, 2015, and April 28, 2016,
and in both versions failed to include information required under act.
"Best Buy's contracts failed to disclose important information such as accurate payment details and the right of the customer to apply for relief on grounds of unforeseen hardship," the commission said.
The first contract was likely to lead customers to wrongly think the company had a right to repossess the goods being purchased.
Commissioner Anna Rawlings said the growing total in fines showed the seriousness with which the courts and the commission regarded this sort of offending.
"The commission urges traders to consider recent prosecutions and to ensure their contracts comply with the law," she said.
Mobile traders use a variety of sales techniques including uninvited direct sales, parking mobile truck shops in prominent locations and using social media.
They sell predominantly or exclusively on credit, layby or other deferred payment terms.