this might not be the right place to ask but does anyone know how costly it could be to take these guys to court ?

no it does not sound right to me either, i cant understand how you can trick someone into thinking that they are buying a residential property.This is the first time anything like this has happened  to my dad , he is a conservative person of reasonable intelligence

http://www.abetterchoice.com.au/company.html  this is the company . Could someone please tell me how common it is for a commercial property in   Melbourne  to decrease in value by 20% after almost  6 years  ? thanks any response