30 minutes later and I have found out how to solve it
Basically I had to make my Variables into a Structure instead of trying to dynamically calling them
S.Var1 = [10, 5, -1, 2, 3]
S.Var2 = [5, 6, 7, 8]
List = fieldnames(S)
[indx] = listdlg('ListString',List,'SelectionMode','Single')
Var_Chosen = S.(List{indx})
Var1_A = Var_Chosen(1)
This gave me the correct value from the Variable which I was looking for
Var1_A = 10