invoice. The invoice(s) shall be submitted to Vendor upon each completion of the service, and total sum collection of each invoice will be THB 32,000.- (thirty-two thousand Thai Baht only). Collectively, there will be total four (4) invoices throughout the service period of one (1) year. In the event that the cleaning service are not able to meet 4 times within the one-year timeframe as contracted under the customer’s defaults, unless otherwise receive the written notification from OHTL to delay cancel the service under this contract, Air-Tech shall invoice all remaining balance of the service fee to the customer within 30 days.