I would be grateful if someone could help me to correct my letter.

Dear Mr. X

Further to our technician (Mr. Y) site inspection regarding to the water seepage at Flat 1F ceiling of ABC building dated 10 Oct 06, simple water test shall be conducted at Flat 2F of bath tub to verify the seepage issue as result of our discussion. Therefore, the test shall be arranged by you in liaising with the Flat 2F of owner for resolving the water seepage issue.

It would be appreciated if you could reply the test date early in order to convenience our manpower arrangement.
Hi Ben,

Dear Mr. X

Our technician conducted a site inspection on 10 Oct 06 regarding water seepage in the ceiling of Flat 1F in the ABC building. As we have discussed with you, we would now like to perform a simple water test on the bath-tub in Flat 2F to clarify the seepage problem. Can you please arrange a date for this test with the owner of Flat 2F?

We would appreciated it if you could advise us of the test date as soon as possible.

Best wishes, Clive
Thanks Clive

Would you mind to give me comment on my letter such as poor grammatical structure?

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Hi Ben,

Here are a couple of suggestions.

1. Generally, try to keep your sentences short and simple.

2. Try to use active voice rather than passive voice as much as possible.

Best wishes again, Clive