Councils have been inundated with requests for help in completing census forms.
Residents are turning to district councils for help even though the local authorities are not responsible for the count.
Switchboard operators have to direct people to the helpline run by the Office for National Statistics.
A spokesman for Lewes District Council said its switchboard operators had taken more than 100 calls from people having trouble.
Switchboard operators and reception staff at Brighton and Hove City Council were also being called upon for their help. Some residents do not yet have their forms, which are due to be returned on Sunday.
Census officials were today taking urgent action after a record number of people swamped telephone helplines asking for help in answering the questions.
The number of helplines was increased from 400 to 870 last night following 240,000 calls on Monday. The number of operators is expected to rise to 190 in the run-up to Sunday.
The census is the UK's largest survey and takes place every ten years.
The confidential questionnaire, which contains 41 questions, asks about subjects including personal health, ethnic group and employment.
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