Residents in Brookmead, Trowbridge, want action after a grassed area played on by children was left in a mess by contractors installing a sewage tank for Wessex Water.
Wessex Water carried out the work to increase the capacity of the sewerage network and allow for a recent new development in the area, reducing the likelihood of flooding during intense rainfall.
The work began at the end of last year and was due to be completed in early March, but the site is still fenced off and has not been returned to its original condition, as residents’ say they were promised.
Resident Eamonn Doyle wrote a letter to Wessex Water and Wiltshire Council complaining about the situation and asking the company to restore the land so children can play on it during the summer.
Mr Doyle said: “A notice on the site prior to work being carried out stated the area was to be restored to its original condition.”
Paul Weightman, who lives opposite the park with son Jamie, seven, said: “We were told there was going to be nothing there, just a tank under the ground, when they finished.”
A spokesman for Wessex Water said the company had since been to see the residents to apologise for the delay and to provide an update.
George Keast, Wessex Water spokesman, said: “We have not been able to complete the scheme following recent weather that prevented us from carrying out excavation work.
“We apologise for any inconvenience caused by the delay and hope to complete our work, if weather allows, as soon as possible.”