A hospital trust has apologised for the treatment a four-year-old heart patient received on a controversial ward after his parents branded his care "shambolic".
Steve, 47, and Yolanda Turner, 45, said they found some of the evidence they heard during the 10-day inquest into the death of their son Sean "shocking and unacceptable".
They told the hearing how they begged doctors and nurses on Ward 32 of Bristol Children's Hospital to help their desperately ill son.
Mr and Mrs Turner, from Warminster, Wiltshire gave harrowing accounts of their son's care and treatment during a six week stay at the hospital, which is regarded as a centre of excellence.
They said Sean was so desperate for a glass of water that he resorted to sucking the moisture from tissues used to cool his forehead.
Mr and Mrs Turner accused doctors of transferring their son to Ward 32 from intensive care too soon and said they missed the signs of his worsening condition - with rising blood pressure, vomiting and fluid loss from his chest.
Sean's parents also criticised the University Hospitals Bristol NHS Trust, saying they did not believe it had learned lessons from their son's death.
"We still have concerns about the failures that we have heard about in this case and that of Luke Jenkins," they said.
"Although Sean needed a high level of nursing attention, at times on Ward 32 he didn't even receive the most basic care.
"There was a lack of leadership, accountability and communication. All of this is shocking and unacceptable to us.
"There did not seem to be a plan for Sean's care, which was disjointed and, in our view, shambolic.
"We are relieved there have been changes made at the unit since Sean's death but we remain concerned that the risks to patients at Bristol may still be very real.
"We have not seen enough evidence to persuade us that the lessons of Sean and Luke Jenkins' deaths, less than a month apart, have been learnt."
Mr and Mrs Turner added: "There were many missed opportunities to rescue Sean from his desperate situation.
"In our opinion, Sean was in the wrong hospital with the wrong surgeon. We now have to try and rebuild our lives without our little boy."
Sean died in March 2012 from a brain haemorrhage after previously suffering a cardiac arrest - six weeks after he underwent vital corrective heart surgery.
His parents, a carpenter and a foster carer, claim their son's death was not isolated and other children with heart problems have died at the hospital.
Up 10 families are believed to be taking legal action against the University Hospitals Bristol NHS Foundation Trust over treatment on Ward 32.
Together with the parents of seven-year-old Luke Jenkins, from Cardiff, Mr and Mrs Turner complained to the independent healthcare watchdog, the Care Quality Commission.
The CQC carried out an unannounced inspection and issued a formal warning to the hospital about standards on Ward 32.
It declared it failed to meet three essential standards of patient safety - on staffing levels, staff training and support, and overall care and welfare of patients.
A five-bed high dependency unit has now been set up on Ward 32 and the trust commissioned its own independent review of paediatric nursing across the hospital with its findings implemented.
Trust chief executive Robert Woolley apologised to Mr and Mrs Turner and said the trust always sought to improve services.
"The coroner has heard that their son Sean was born with a very rare and complex heart condition and was undergoing a procedure which carries a known risk of death," he said.
"But the inquest has also highlighted some missed opportunities in the care we gave to Sean when managing his post-operative complications and shortcomings in our communication with the family.
"I would like to offer my sincere apologies to Mr and Mrs Turner for the additional stress that we have caused them in relation to Sean's death.
"We are always improving our services and we have made significant changes since Sean was on the ward in early 2012."
Avon Coroner Maria Voisin recorded a narrative conclusion saying in her view there were "lost opportunities" with Sean's treatment but said this did not amount to neglect because there was not a "gross failure to provide basic care".
She also said she would not be writing a prevention of future deaths (PFD) report because of the changes the trust had made since the boy's death.
"Sean Turner died on March 15 2012 from complications from the Fontan operation undertaken on January 25 2012," she said.
"Following surgery he developed excessive fluid loss from his drains; elevated pressures in the Fontan circulation; the development of a thrombosis.
"The thrombus required treatment and Sean and died due to an intra-cerebral haemorrhage which is a known complication of the treatment of thrombolysis.
"In addition there were lost opportunities to render medical care or treatment to Sean in this post-operative period which included management of his anti-coagulation from February 6 and not considering fenestration between February 8 and 16."