She said they are "currently still interpreting the decision and no decision has been made whether to appeal or not."
Ms Lendich said the outcome will have repercussions for many industries, not just hospitality.
Mrs Williams went to the Ministry of Business, Innovation and Employment three years ago with the lieu day issue after she had been working at the Hornby restaurant for a year.
Wendy's, which has 23 outlets in New Zealand, including one in Hereford St and in Hornby, has breached two sections of the Holidays Act 2003.
Ms Lendich said they have been using the 'three week' rule to determine who is entitled to alternative holidays.
"… a person who works the same day of the week as the public holiday for the three weeks prior to the public holiday and the public holiday itself is due an alternative day," she said.
Ms Lendich issued a notice to all her employees last week, letting them know about the situation.
"However the decision does not mean that everyone will be paid an alternative day for working a public holiday," the letter concluded.
Unite Union, of which Mrs Williams is a delegate, has estimated it would cost Wendy's $1.6 million to pay back employees' leiu days.
MBIE senior labour inspector Kim Baldwin found Wendy's breached section 56 and 60 of the Holidays Act.
Section 56 says an alternative holiday must be provided to an employee who works on a public holiday if that day would otherwise have been a working day for them.
Section 60 sets out how those employees should be paid for the alternative holiday.
Wendy's has been ordered to comply with the two sections, conduct a review of its restaurants and keep records of staff contacted, rosters and leave.
It has been ordered to give all past and present employees from the Hornby and Dunedin restaurants their alternative holidays, or the equivalent pay since the restaurants were opened.
Wendy's has also been ordered to do the same for all other restaurants across the country backdated to July 1, 2012.
Ms Lendich said they thought their interpretation of the law was right and it's incorrect to say Wendy's employees have not been receiving alternative holidays.
But Mrs Williams believes Wendy's purposely change their employees shifts so they don't get lieu days.
Ms Lendich said laws about pay need to be black and white and the Holidays Act 2003 needs a "total overhaul."
"Politicians should be more aware of the laws they make around these issues and be totally clear on what the law actually is," she said.
But Mrs Williams said the law doesn't need changing.
She told Southern View she's had a lot of support from co-workers and friends.