Thousands of customers were told of the sudden cancellation of their trips via email, with HotelQuickly then posting a statement on its Facebook page.
"Unfortunately, due to an unforeseen issue with our main hotel supplier many reservations have been cancelled," the message said.
"We fully understand how disappointing this situation is and we are working very hard to come up with a manageable solution.
"However, at the moment and until a solution is in place, we can only offer you a refund in the form of a credit voucher for the value of your original booking that you can use for a future reservation."
News.com.au has approached HotelQuickly for a comment.
Many stung travellers from around the world have accused the company of scamming them.
"It looks as if HotelQuickly are either conning, defrauding or going bankrupt," customer Les Davis told the Independent.
"Not sure how many people have lost money with this outfit but I contacted them through TripAdvisor and made a booking for two nights in Bryce Canyon, US, for a trip next May.
"The hotel confirmed the booking which I stupidly paid in full by debit card at the time of booking."
West Australian woman Debbie Hamilton had booked two luxury resorts through HotelQuickly for a holiday in Thailand with her husband over the summer.
She got HotelQuickly's email that both bookings had been cancelled on December 9.
"I rang both hotels, and they both said the booking had been made but cancelled on December 6,' she told Daily Mail Australia.
"I frantically re-booked straight away, but had to pay an extra $400 all up for the booking, as it was peak time."
Mrs Hamilton said HotelQuickly sent her online vouchers as a refund for the $1200 she had paid for the bookings, but the vouchers had a broken link, rendering them useless.
"I felt like someone had come in and burgled me," she said. I felt very vulnerable and I was panicking that the bank wouldn't come to the party."
Another customer, Christopher Cotton, had the same problem with the credit voucher he was sent.
"When you try and use the voucher they offer, there are either no hotels or it states the voucher has been used before. It's a worthless voucher," he told the Independent.
Angry customers have also lashed out at TripAdvisor and Trivago, which directed many of them to HotelQuickly.
"@TripAdvisor why are you still advertising HotelQuickly on your site when they have clearly scammed a lot of people," John Tweedie tweeted.
"My wife meant to fly to Fuerteventura at 6 in the morning and we received a cancellation email today, money gone."
Another Twitter user, Simon Ledger, said to Trivago: "HotelQuickly is scamming your customers, cancelling all bookings prior to the date and offering future vouchers in exchange instead of refunds, can you help contacting them to resolve the issue please?"
In a statement to news.com.au, TripAdvisor said there were a number of things customers should do if they were impacted by HotelQuickly.
"We are very concerned to hear about the difficulties some HotelQuickly customers are experiencing with their bookings," a spokesperson said.
"We advise anyone who has been impacted by this matter caused by HotelQuickly to do the following.
"Locate your confirmation email and HotelQuickly booking reference number.
"If a payment was already processed on your booking, please contact your Credit Card provider to dispute the charge from HotelQuickly letting the credit card company know you believe the booking has not or will not be fulfilled.
"If a payment has not yet been charged to your account, please contact your Bank or Credit Card provider to ensure any future payment is blocked.
"Check your travel insurance documentation to see if you may be eligible for compensation.
Look for alternative accommodation as soon as possible."
News.com.au has contacted Trivago for comment.
