Was away for a few days,my young son was playing his cds on radio and had fan on I think.Anyway wont start ,got a jump {was that wise?} it started drove for 20kms or so,left it for an hour and she started fine.Following morning would not start.Battery 2 months old bought it from Halfords.I note from other threads that maybe that was not a prudent choice.Any ideas or recommendations? Should I get merc battery?E320 PETROL ESTATE 1997