While the telco-turned-sports streamer has insisted there have been no reports of any "buffering issues", several customers were left fuming over issues ranging from buffering and audio timing, to freezing and apps playing up during the first of the weekend's four quarter-finals between England and Australia.
Several customers complained on Spark Sport's official Facebook page even before the kickoff at 8.15pm in Oita.
At least one pub owner complained about having to deal with customers upset over "useless" streaming.
Spark Sport spokesperson Althea Lovell told the Herald there had been "no issues with the Spark Sport streaming platform".
"There are some customers who are clearly having problems tonight relating to their in-home connectivity, tech or devices. We are working hard to help these customers with their individual issues," Lovell said.
"The audience for the England vs Australia quarter-final has already reached a new record for Spark Sport and while this is not creating any capacity issues with the service, we are seeing a corresponding increase in customers with individual issues."
Another user called it a "bloody joke" while several pleaded with Spark Sport to switch to free-to-air and to give them full refunds."Wish we'd seen it. Sounds amazing," said Anna Godsalve on the Spark Sport Facebook page under a post showing one of England's first half tries.
"Unfortunately the picture froze for almost 10 mins. Score jumped from 5-3 to 14-6 without us seeing it," she added.
"Spark you can give me a full refund I gave you benefit of the doubt but you've stuffed this up big time can't even watch the English Aussie game which I've been looking forward to all day," said Angela Louise on the same post.
"Fibre, Ethernet, reset after reset, tried 2 iPads and iPhones missed 20 mins... now we are sitting in front of a 65 inch watching intermittent bits between all, come on Spark let us watch our beloved game live on uninterrupted tv," said Ariana Te Moabna-Lyttle.
"And it's gone again. What are you going to do about this terrible coverage spark sport?" said Adhamh O'Fiach.
A Spark Sport employee replied and said "Hey Adhamh, sorry to hear that - no issues on our end. Can you please get in touch with our support team."
There was positive comments on the Facebook page.
"Perfect image and quality coverage thanks again Spark," said Jacqui Wilson.
"Awesome streaming not a problem," added Lexy Reid.
"Looks absolutely perfect here, not one issue," Jason Williams said.
Last month, Spark Sport offered full and partial refunds to customers after the streaming of the All Blacks' World Cup opener against South Africa experienced severe disruptions.
The match was moved to TVNZ channel Duke at half-time on September 21 after the serice cut out.
The All Blacks' quarter-final clash against Ireland kicks off at 11.15pm tonight with a delayed broadcast on Duke.