Complaints against beauty parlors fell by 7 percent last year, but there were still some extreme cases, according to the consumer watchdog.
The Consumer Council said it received 1,148 complaints.
But chairman Wong Yuk-shan said there were many complaints regarding sales practices.
"Despite the decline, dissatisfaction over prepayments, including expiry of coupons and alternation or termination of contracts, were up 82 percent and 292 percent," he said.
In an extreme case, he said, a woman was lured with a trial offer of HK$88, but ended up buying services that cost HK$1 million. Although entitled to 990 sessions, she found the contract was valid for only six months.
She paid a HK$500,000 deposit by credit card, and was repaid only HK$30,000 upon asking for a refund.
Council chief executive Gilly Wong Fung-han said "having only a six-month expiry period with half-a-million-dollar contract is quite outrageous for any one with common sense."
Wong also said many consumers regretted signing contracts they were hounded into signing.
She urged the government to implement a cooling-off period.
Also received were 57 complaints over "suspected unsafe" medical beauty services, such as high-energy laser treatments and invasive surgical treatment, up by nearly 55 percent.
The council received a total of 24,881 consumer complaints last year, a slight drop of 1 percent from the previous year.
It also said the number of complaints relating to online purchases and budget airlines had risen.