Private firm Serco, which provides community healthcare across Suffolk, has been criticised for failing to meet key response targets.
Serco took on the £140m three-year contract to run community health services in Suffolk in October 2012.
Labour spokesperson for health on Suffolk County Council Sarah Adams has criticised the firm for not meeting targets.
Serco said its work in Suffolk was providing "some excellent results".
Ms Adams said a new report from Serco to the council's health scrutiny committee showed that Serco was not hitting three of their key performance indicators (KPI) in community health response times.
For example, it failed to meet urgent four-hour response targets - for nurses and therapists to reach patients at home 95% of the time (only achieving 89.3% in November 2013).
Before Serco took over, the target was achieved 97% of the time.
Ms Adams said: "The fact they are providing a significantly worse service than previously is of huge concern."
She called on Serco to make publicly available its performance on the 188 performance indicators.
She said at present only a minority have been released.
Conservative county councillor Tony Goldson, chairman of the health scrutiny committee, called for more transparency from Serco.
"We will be looking to see what has been done to in regards to improvement at the next meeting in April."
On Wednesday, an NHS review of services provided by Serco in Suffolk concluded that there was "no evidence that the programme of change being implemented by Serco has resulted in any harm to patients".
Abi Tierney, Serco development director, said: "We are delivering some excellent results.
"Average length of stay in our community hospitals reduced by a week in the six months to November 2013. Our care co-ordination centre is open 24 hours a day all year round. This was not the case before Serco took over."
Serco runs a range of services including community hospitals in Aldeburgh, Felixstowe, Ipswich and Newmarket, as well as community dental care and a range of children's services.