Please advise if the below is gramatically correct? (i need to send this as an email)?

To avoid any operational disruption first we will send you two cars for service and once completed we would thereafter send you the remaining two car

To avoid any operational disruption first we will send you two cars for service and once completed we would thereafter send you the remaining two cars for service.

or:To avoid any operational disruption first we will send you two cars for service and once completed we would thereafter send you the remaining two cars for service.

Tags:service,services,