YOU SAID:

I only call you when it's half past five.

INTO JAPANESE

五時半になってから電話します。

BACK INTO ENGLISH

I will call you at 5:30.

INTO JAPANESE

5:30に電話します。

BACK INTO ENGLISH

Call at 5:30.

INTO JAPANESE

5:30に電話してください。

BACK INTO ENGLISH

Please call at 5:30.

INTO JAPANESE

5:30に電話してください。

BACK INTO ENGLISH

Please call at 5:30.