HexSys Size Plugin for Virtuemart, use of comma

Hello,
I have purchased the HexSys Size Plugin for Virtuemart plugin for calculating the price by width and height, and works fine if I use dot (.) for the decimals. (ex. 1.5)
Although there are many users that use comma (,) but in this case the resault is wrong (eg. if the price per square meter is 20 and the user inserts 1,5x1 calculates price = 20, instead of 30).

I would like either the comma to be accepted giving the correct resault either to show an error message informing the user so as to use dot instead of comma.