An upmarket beauty centre that costs at least $20,000 to join has shocked members by suddenly closing, citing an 'air-conditioning problem'. A notice on the door of Spa Retreat, in Duddell Street, Central, said it would reopen on August 31 and that all appointments had been cancelled. Members, who were not informed in advance, were dumbfounded when they turned up at the centre to find it closed. Some left messages on the door, criticising the company for not notifying them beforehand and questioning whether money they had deposited would be returned. 'How could you shut down for such a long time? It's completely unacceptable,' read one message. Ku Wing-yan, who joined the centre last July, said members had to pay a deposit of at least $20,000 to join. She still has $16,000 in unused credit, which she doubts she will get back. 'I'm not sure if they will really open again. I have called the office but no one answers my call. If it was because of the air-conditioning failure, how come there are no people in the office repairing it?' She said she had lodged a complaint with the Consumer Council and was considering reporting the case to police. Ms Ku said there were about 20 staff working at the centre. Spa Retreat is one of the most upmarket beauty centres in Hong Kong, charging $480 for a 25-minute spa massage and $980 for 85 minutes of facial treatment. 'We apologise and will reopen for business as soon as possible,' the notice on the door read. Calls to the centre went unanswered yesterday and there was no sign of anyone repairing the air-conditioning system inside. A security guard at the building where the company is located said Spa Retreat staff had not been seen since Sunday. Spa Retreat, which opened in 1997, promotes itself as one of Asia's best spas, providing 'the perfect environment for sensory indulgence, relaxation and rejuvenation' and offers a range of more than 100 treatments and packages. Police said they had not received any complaints. A spokesman for the Consumer Council warned the public to be careful when subscribing to services that required payment in advance. 'There's always the danger that the consumers may not be able to get their money back. They should think before joining such plans,' he said. Spa Retreat could not be reached for comment despite repeated calls yesterday. There was nobody in the office during visits by South China Morning Post reporters yesterday and on Tuesday.