Karen Collins pleaded guilty to being over the limit, but said a breathalyser reading of 100 microgrammes of alcohol in 100 millilitres of breath - which put her at more than three times the legal limit of 35 microgrammes - was wrong.
Collins, 50, of Quines Hill Road, Forest Town, was reported to the police at 5.45pm when she reversed her silver Vauxhall Corsa into a parked vehicle at the Texaco service station on Clipstone Road West.
Mark Stocks, mitigating, said: “The police didn’t manage to get hold of her until 7.20pm and that’s when a breath/alcohol reading of 100 was taken.”
Mrs Collins told police she had drunk three bottles of beer during the afternoon of on November 10, 2015, while celebrating her mother-in-law’s birthday, but had consumed two more glasses of wine since returning home.
The court heard that Mrs Collins worked as a mobile home help and was bound to lose her job as a result of the incident.
She had driven to the service station because she believed she had left her purse there.
Eye-witnesses told police Mrs Collins had dumped five wine bottles into the bin at the service station.
Mr Stocks said: “The most that can be said is that the reading was not 49 and it wasn’t 100 because everyone accepts that she drank after she had been driving.”
Experts performed a forensic back calculation which estimated that Mrs Collins had between 66 and 93 microgrammes of alcohol in her breath at the time she drove.
The court heard she had no previous convictions and had a clean driving license.
Magistrates banned her from driving for 18 months, fined her £120 and ordered her to pay costs of £85 and a victim surcharge of £20.