AddOrUpdataDataTableEntry Service is part of a DataTable Thing Entity. So, if you are using a DataTable Thing then you will see this service.
For your case; you can create your own custom service which will take input as infotable and update the infotable property in the Thing.
Then use this service in your Mashup to pass the updated data.
I hope it helps.
My problem is that I have created separated properties for the thing (one for each data to display or modify)
So I have to create a DataTable with these datas inside (instead of having them one by one and using "all data" to fill the grid) ?
And after put this Datatable as prpoerty of the thing ?