The family of a diabetic 82-year-old woman, who wanted to lose weight for health reasons, visited a branch of London Weight Management in 2013 after seeing its TV commercial touting a weight-loss trial session for $18.

They were eventually persuaded into signing a nearly $400,000 package with the slimming centre.

The treatments not only failed to improve her health, but they also caused Madam Gan Siew Hong to suffer diarrhoea, a skin rash and pus discharge, she claimed in a lawsuit filed in the High Court seeking compensation of close to $450,000 from the slimming centre.

Madam Gan, now 85, wants a full refund of the more than $400,000 her son paid for weight-loss treatments and products.

She is also seeking damages of about $41,000 for medical fees incurred in treating the alleged adverse effects of the services.

In court documents obtained by The Straits Times, Madam Gan claimed the centre repeatedly pressured her, her son and her husband into signing up for the package.

On July 23, 2013, she, together with her son, Mr Tan Kok Wah, and husband, Mr Tan Ee Leong, went to the centre's Ngee Ann City branch after seeing its commercial.

She said her son and husband had asked for a medical assessment before starting the programme but were assured by the therapist that it was suitable for her.

Apart from diabetes, she has a heart condition, high blood pressure, kidney problems and water retention in her legs.

At the trial session, her son was persuaded to pay $10,914 for an eight-month package. Six days later, while she was going through her third session, her son and husband were "brainwashed" into extending the package to two years for an additional $66,768.

Her son paid a portion using two credit cards, and a therapist accompanied the family home to collect a cheque for the balance.

Two days later, Madam Gan was made to believe that she needed more than two years to see progress, the lawsuit claimed.

A therapist again accompanied the family home, where her son made out two cheques totalling $321,000 for a six-year package.

He also paid $4,662.40 for "detox drinks", which allegedly caused her to suffer diarrhoea, and $3,595.29 for ginger masks to reduce the swelling in her legs. After she was told by a skin doctor that the rash on her abdomen which oozed pus was an allergic reaction to products applied on her skin, she returned to the centre for more treatments. She finally stopped in June 2014.

In its defence, London said it is willing to refund her the unused portion of the package amounting to $43,408.15 out of goodwill.

The centre said Madam Gan's family declared only that she had diabetes and that it is not liable for injuries resulting from non-disclosure of medical history.

The centre also said it had advised her to seek medical advice on the suitability of its treatment and products and told her that successful weight loss depended on a balanced diet and regular exercise.