Dear Khun Piyawat ,
Please kindly adjust your Fuel charge after adjust under correctly & follow on the contract = 1.8% X 4 = 7.2% not 7.5% .
Due to our staff got from คุณตุ๋ม which Kohler A/C use 7.5% .
Please confirm & advise due to our accounting will issue invoice billing accordingly. Thank You