Pam Wheeler, 76, who had had cancer surgery, said her carers persuaded her to make a phone call confirming they had visited when they had not.
The care provider Penhellis Community Care said an investigation was under way with Cornwall Council and it could not comment further.
The council said an alternative provider was being sought.
Mrs Wheeler said she was supposed to be seen four times a day, but visits were inconsistent.
The Wheeler family said some of the carers told her if they did not make the planned visits they would not get paid, then asked her to ring numbers which logged visits on an automated system - even though no one had come to the house.
The monitoring of care workers requiring them to dial in to clock in and clock out was introduced by Cornwall Council to ensure they spent enough time with elderly and vulnerable clients.
Mrs Wheeler said carers called her to ask her to clock them in and out over the telephone.
"So they got paid but they never visited," she said.
The claims relate to three specific carers. Mrs Wheeler's daughter Diane said the other carers supplied by the care company had been very good.
She said her mother "thought she was helping them getting some wage" and "being friendly" by doing as they asked.
Penhellis Community Care confirmed Mrs Wheeler's care package had been handed back to Cornwall Council.
Cornwall Council said it was "talking to the care provider and will be liaising with the family to hear and act upon their concerns, review their needs and discuss how to meet those needs whilst an alternative provider is sought".
Care workers asked a client to fake their visits because they were under so much pressure, it is claimed.