You want to update valuation data of services in batch mode.
However, it is not possible with data migration, mass data maintenance or even webservice.
SAP Business ByDesign
Updating valuation data of services thru migration template will be available in 1911 release.
Currently, you can only update service valuation data manually.
2446828 tells that webserive cannot be used to update service valuation data.
Service Valuation Data, Migration, 批量更新，服务评估数据 , KBA , AP-FMD , Business ByDesign: Financial Accounting Masterdata , Problem