"He's ashamed of betraying the trust of his parents. He is lucky they have offered him unconditional support and he's back living at home."
Cairns bought male and female clothing, footwear and fashion accessories, fast food, groceries, auto accessories and alcohol.
He also used the card to obtain large amounts of cash which he spent on Kronic and petrol.
He originally faced 53 separate charges for his offending while on a community-based sentence, but four were amended to representative charges of dishonestly and without claim of right using a document to obtain pecuniary advantage.
The others were withdrawn.
Judge O'Driscoll said Cairns had no previous convictions for dishonesty-related offending.
On each charge the teenager was convicted and sentenced concurrently to four months community detention with a curfew from 7pm Friday to 7am Monday, as well as 200 hours of community work.
He was also sentenced to 12 months of supervision with a special condition for him to undertake counselling or treatment for drug and alcohol dependency as directed by the probation service.
He was ordered to pay reparation of $12,495.66 to his parents at a minimum of $20 a week.
Cairns also admitted an unrelated charge of breaching community work by failing to report to probation on April 7, for which he was convicted and discharged on the basis the sentence had subsequently been completed.