The Mobile Shop prosecution is the 13th case taken by the commission since it undertook a report in 2015 which found widespread non-compliance in the industry and brings the fines across the industry to $1.56 million.
Rawlings said of those it had prosecuted Mobile Shop's contract was the least compliant.
"We had advised Mobile Shop in 2015 that we did not think that its contract complied with the law, but the company didn't change its contract," she said.
"All of Mobile Shop's contracts lacked basic information such as the number of payments and an accurate statement about cancellation rights.
"Most sample contracts viewed by the Commission also failed to state the payment amount and when the first payment was due. The wording was confusing and error-ridden and the contracts were in small font making them difficult to read."
In sentencing, the company Judge Patrick Treston said the number victims was significant and they were "particularly vulnerable."
But he noted the company was also close to being completely wound down.
Rawlings said the case was the last prosecuting arising from its follow-up to the initial report but it was not the end of its enforcement.
"We have a number of investigations open and we will continue to take appropriate enforcement action against traders which fail to meet their legal obligations to their customers," she said.
Rawlings said it had noticed that compliance was improving.
"Traders are coming back to us with new contracts and they are generally better," she said.
Since it issued its report in August 2015, 18 out of 32 traders had either closed down, stopped making new sales or exited the business.
