please correct this letter, thanks

We have located a new courier company called Speeding Shuttle Courier Service Company to provide us local courier service. We will commence hiring their service on 4/6. Should you require such service, please fill in the new courier form and call their hotline at 2391 2832. For further information, please kindly refer to the attached sheet (or memo or document).
Comments:


"Find the new courier company" is Chinglish. It is better to use the word "located" instead of "find".
This service will start on 4/6 is a bit weird. You should be using other courier's service now. By saying this service will start on 4/6, does it mean you did not need courier service before; or the courier company would commence their business on that day; or you will start using them on that day? I recommend you to use more neutral wording: we will commence hiring their service on 4/6.
Others are just fine tunings of your wording.

"Speeding Shuttle Courier Service Company" is a new local courier service which will start on June 4 .

Procedures are simple, just fill in the form and call their hotline @2391-2832 when you need their service.

Please kindly see the attachment for further informations(一定有s). or
For further informations, please kindly see the attachment.

係唔係要出memo 比公司同事呀???如果係..你可以咁打

With effective on 4/6. Please note that the new courier company "Speeding Shuttle Courier Service Company" will provide local courier service. Plesae fill in the new courier form and call them up at 23912382 for any local courier service.

Kindly please find the enclosed document for further information.

The new courier company "Speeding Shuttle Courier Service Company" will start to provide local courier service on 4/6. If you need to call them to deliver any documents, please fill in the new courier form and call their hotline at 2391 2382, please kindly see the attachment for further information.

We found a new courier company, Speed Shuttle Courier Service Company, providing a local courier service. This service will start on the 4/6. If you need them to deliver any documents, please fill in the new courier form and phone up their hotline : 2391 2832. For further information, please see the attachment.

你封信需要既改動唔大, 幾好.