It is difficult to repair the aluminium pipes in the freezer, there are proprietory compounds, usually epoxy resin, available to effect repair but not always successful. This would entail fitting a schraeder valve to the compressor,evacuating and recharging with probably R134a refrigerant. By the time you have paid the service guy, at what '£30 p hour' ,you may still have had moisture contamination.No real guarantee Sorry sounds like an expensive mistake. Better to switch off overnight.
Keith
August 2010