According to the provided information, I would suggest you one of the following approaches:
1) Create a custom binding list that inherits from BindingList<T> and inside it to call the corresponding methods of the service. Information about the BindingList<T> class is available here
2) Use the event handlers of the grid itself to call the necessary service methods
3) If the service is generated with the Add OpenAccess Service wizard, you could use the step-by-step tutorial provided with the SofiaCarRental - WCF Plain Services with Windows Forms
sample as guide lines. You can open it by selecting the sample and clicking on the OpenDocumentation...
If you have additional questions, do not hesitate to get back to us.
All the best,
the Telerik team