See if the following steps will help,
Open Control Panel -> Clock, Language, and Region -> Region and Language 1,
Under 'Formats' make sure that English - (United Kingdon)
is selected 2,
Under 'Location' make sure that United Kingdom
is selected 3,
Under 'Keyboard and Languages' and 'Change Keyboards' make sure that the 'Default Input Device' is set to English (United Kingdom) - United Kingdom 4,
Under 'Administrative' click 'Copy Settings'. Make sure that both settings at the bottom are selected and click 'OK'
Now try in Excel to see if it has had any effect.
This has helped in gaining additional settings from within certain application within Windows