Staff shortages are holding back improvements in Blackpool's children's services with the department predicted to overspend by nearly £9m in this financial year.
The complexity of care required by some children, which can cost up to £7,000 a week in the most serious cases, is among the reasons for the spiralling costs.
An additional £4.3m has been spent on extra staffing this financial year but there are still 31 vacancies among children's social workers while there is a high turnover of agency staff with many leaving their roles after less than three months.
The extra funding was ploughed in after the department was rated inadequate by Ofsted inspectors in December 2018.
Director of children's services Diane Booth said in a report to the council's children and young people's scrutiny committee "the vast majority of this focused on strengthening social care teams" and "increasing the number of
frontline social workers" as well as reducing caseloads.
But it has been difficult to recruit social workers due to competition for staff from other North West councils.
Ms Booth added in her report: "The capacity to drive forward improvement in practice at the rate that the council would wish has been compromised by staffing sufficiency and stability."
Councillors questioned the level of overspend and repeated concerns about the cost of looking after children particularly in residential care mainly delivered by private operators.
Coun Kim Critchley said the committee needed to see a breakdown of how weekly fees of up to £7,000 were used to care for children with complex needs.
She said: "It's like our kids have become cash cows because they need this emotional help."
Coun David Owen warned the council was running out of money "to make that commitment that every child that comes into this town who needs to be supported, will be supported".
He added: "Our head of service has a problem that is impossible to solve except with money, but there isn't any more."
Blackpool's Conservative group wants more council-run children's homes.
Group leader Coun Tony Williams said: "The council has very little resource to look after these children here in Blackpool.
"Despite continued demand from our side of the council chamber that more accommodation should be developed here in the resor, the council continue to farm out individuals to care resources in other authorities, often hundreds of miles away from Blackpool."