Solenne San Jose, from Pessac in the Bordeaux region of southwestern France, could not believe her eyes when she opened the bill to discover she was being asked to pay 11,721,000,000,000,000 euros to close her account.
"There were so many zeroes I couldn't even work out how much it was," she said.
San Jose's alarm mounted when operators at Bouygues Telecom told her they could not amend the computer-generated statement or stop the balance from being debited from her bank account.
Only after a series of frantic calls did the company finally admit the bill should have been for 117.21 euros.
Bouygues Telecom told AFP the mix-up had been due to a printing error and a subsequent misunderstanding between the client and staff at their call centre.