The five-week promotion will see one Hello Kitty plush toy of a unique design released over the counter every week from 30 May till 3 July for each extra value meal purchase. A 'McDelivery' kitty, termed the 'Witch' kitty by fans, is available exclusively for online orders.

The first week’s promotion was supposed to last till 5 June, but stocks of the 'McDelivery' kitty were reported to have run out at some outlets on the first day of the promotion. 

By Tuesday, McDonald’s confirmed on itsFacebook page that stocks for the over-the-counter 'Wizard of Oz' variety of the Hello Kitty soft toy had run out island-wide.

A large number of the comments following the promotion’s launch were from angry Hello Kitty fans.

“It is extremely disappointing that there are no Hello Kitty toys available! And it's ridiculous that McDonald's is not accepting upfront payment for something that I am entitled to having bought two meals,” said Faustina Chay in a post on McDonald’s Facebook page.

“(McDonald’s has) been in this kitty line before, (they should) know how much Singaporeans welcome them and will queue or do advance order just for them. So why are (they) not prepared for such overwhelming response?” said Irene Ng, another Facebook user that posted on the page.

The 'McDelivery' kitty encouraged fans to order their meals online but disrupted food delivery service.

“I called the McDelivery hotline to place an order but was told that due to overwhelming response for the Hello Kitty promotion, delivery services to my area would be temporarily unavailable,” said Joseph, one of the people who complained about service on McDonald’s Singapore’s page on Facebook.

“The delivery came without the sauces, napkins and straws,” said another customer, Prescilla Huang, on the food chain’s Facebook page. “The food quality was below normal standard. The burgers were cold, fries were soggy and the cans of coke were not chilled.”

In response to queries from Yahoo! Singapore, a McDonald’s spokesperson said that they did indeed anticipate a strong response to the launch of the promotion, and had increased the number of plushies available by 40 per cent from a similar promotion last year. However, the number of orders they received “exceeded even those expectations”.

The spokesperson said fans would able to check which restaurants they can purchase the stuffed cats from at thePlushies Tracker.

“We’d like to advise our customers that the Hello Kitty Fairy Tales collection is available on a while-stocks-last basis,” said McDonald’s.

The fast-food chain also assured that affected customers that have lodged a complaint will each receive a personal call from a customer service representative.

“We sincerely apologise for any inconvenience caused and would like to assure our customers that our teams are hard at work both to improve our ability to meet customer demand, as well as our McDelivery response speed,” said McDonald’s.

This is not the first time that McDonald’s has gotten Hello Kitty fans all riled up. The Hello Kitty “craze” that happened back in 2000 in Singapore when McDonald’s launched the plush toys on New Year’s Day saw fans getting injured in fist fights and forced the chain to hire private security personnel to control the crowds.

Meanwhile, the ‘Little Red Riding Hood’ plush toy will be available in the second week of the promotion from midnight this Thursday, 6 June.