The mother of a nine-year-old girl with severe epilepsy wept as she had an illegal supply of medical cannabis confiscated by customs officials after entering the UK with the potentially life-saving medication that her daughter cannot access, despite changes in the law.

Campaigner Emma Appleby flew to the UK from Holland on Saturday morning carrying three months’ worth of cannabis oil, valued at £4,500, for her daughter Teagan, who has a rare chromosomal disorder as well as Lennox-Gastaut syndrome, which causes up to 300 seizures a day.

It follows a similar course of action by Charlotte Caldwell last year, whose audacious attempt to challenge what she said were the UK’s unjust laws helped pressure the government into legalising medical cannabis. She had the medicine returned within a week after her son Billy’s seizures returned and he was admitted to hospital.

Appleby, from Aylesham near Dover, said she was “devastated” that she was not allowed to enter the UK with the appropriate medicine for her child, adding she had been “passed from pillar to post” trying to access it in the UK. This prompted her to secure a prescription in Rotterdam after her request for an import licence on compassionate grounds was refused.

“I’m devastated. I’ve always tried to do the right thing. I’ve jumped through all the hoops but ended up being passed from pillar to post and being met with a flat ‘no’,” she said. “All I want is the best thing for my daughter. To have the medicine taken in this way is deeply upsetting.

“But I will fight to get it back and fight so that other parents in the same situation as me don’t have to go through this.”

On Friday, she said that a succession of pharmaceutical drugs and diets had failed to alleviate her daughter’s symptoms, with a number of the medicines causing severe side-effects. “Whilst the NHS and the medical professions are having arguments over what constitutes evidence, my child is suffering every day,” she said. “I am at my wits’ end.”

Appleby has met the health secretary, Matt Hancock, who told her at a meeting in Westminster in March that he understood the frustration and pain among families and recognised something has to change, but he conceded practical changes need to be clinician-led.

The law in the UK was changed last November to make access to medical cannabis legal, but parents have been struggling to secure prescriptions, in part due to reluctance within the medical community, with the Royal College of Physicians and the British Paediatric Neurology Association largely discouraging use of the medicine.

NHS England guidance says it expects cannabis-based products for medicinal use should “only be prescribed for indications where there is clear published evidence of benefit” and in “patients where there is a clinical need which cannot be met by a licensed medicine and where established treatment options have been exhausted”.

Hannah Deacon, a campaigner and mother of Alfie Dingley, one of the first children to be prescribed medical cannabis, comforted Appleby at Southend airport. She said: “Vulnerable people are having to raise money to go abroad, and they need help from the government, rather than an insistence on randomised control trials to prove the efficacy of medical cannabis.

“These are not appropriate for cannabis, a plant with around 400 components. We need observational trials and modern thinking from clinicians and ministers to make these life-changing medicines truly accessible. Our children do not have five years to wait for change to slowly take effect.”

The Labour MP Tonia Antoniazzi, the co-chair of the all-party parliamentary group on medical cannabis under prescription, said: “That a mother of such a sick child as this has been driven to take these desperate measures is a damning indictment of how this policy has been implemented.

“The government did the right thing in changing the law. But everyone involved with the implementation should hang their heads in shame.”

A government spokesman said: “The decision to prescribe cannabis-based products for medicinal use is a clinical decision for specialist hospital doctors, made with patients and their families, taking into account clinical guidance.

“It is unlawful to import unlicensed cannabis-based products for medicinal use to the UK without the prescription of a specialist doctor and a Home Office importation licence.”