Matcha or Macca?

For some time now one customer has been referring to out Matcha latte as a "Macca" Latte ( I tried to spell it how she says it). After much debate between us all at work a few of us looked it up.
She sound an herb by the same spelling. As for myself I stumbled across a web page talking about how "Matcha" is the Canadian way to say it.
After much debate, it makes sense. Ma-ccha is the only way the Japanese can say this variety's name. The "t" is purely our own invention.
On another note, perhaps I am wrong. I am going to be starting regular Japanese lessons in April, I hope to be able to bring this up with Taka-Sensei. Till then, what do you think of these two ways of writing the name of this tea in the American/English language?