Operators $\square,$ $\Diamond$ and $\rightarrow$ are defined by: $a\,\square\,b=\frac{a+b}{a-b};\, a\,\Diamond, b=\frac{a+b}{a-b};$ $a\,\rightarrow\, b=ab.$

Find the value of $(66\,\square\, 6)\rightarrow(66\,\Diamond, 6).$