Want to Cut Cable TV Service

I have filled out the Cable TV Service Termination Form on-line on March 20. They said they will mail me the 終止服務確認書, the 確認書 will confirm my termination and tells me where I should return the 解碼器.

I have called them again on April 7, and April 17, they said they have received my form and termination is confirmed. But up till today, I still have not received the 終止服務確認書. I called CS (1832832) again and they said they ahave already send to me 2 times, I said the address is same as the billing address and I dunno why I can receive the bill but not the letter.

My termination date is May 14, but can I return the 解碼器 before May 14?

I know the address to return the 解碼器, but when I go, do I need to bring my 終止服務確認書 together? Anything else I need to bring?

Thanks