Checked in early for Sydney-Perth flight via the Jetstar App. Notified of a 45 minute delay and received Boarding Passes with a boarding time that reflected the delay. We presented at the bag drop 1 hour prior to 'our scheduled departure time' to be told that the service was closed and consequently we missed our flight - We later found out that there was in fact no flight delay despite our Jetstar issued boarding passes indicating otherwise. Very poor customer service from Jetstar duty manager on the night who refused to accept the error despite all my screenshots and evidence. With two step children late at night, I had to organise overnight accommodation and new flights home at my cost. Jetstar reimbursed the missed flights (and dare I say accepted some responsibility for the error) however I am still out of pocket over $1100 which I incurred as a direct result of this.