Hi Mia,
Thank you for your update.
Essential grid control has builtin support for importing excel file contents into grid using GridExcelConverterControl class.
Syncfusion.GridExcelConverter.GridExcelConverterControl gecc = new Syncfusion.GridExcelConverter.GridExcelConverterControl();
gecc.ExcelToGrid(@"../../test.xls", this.gridControl1.Model);
this.gridControl1.Refresh();
Sample attached for your reference.
http://files.syncfusion.com/support/Grid.Windows/91343.zipPlease let me know if this helps.
Regards,
Jisha