I have tried to recreate the issue and have a suggestion to address it (Attached Image for Steps described below)
1. Data represents hypothetical Point layer (Customer point locations) and Polygon layer (representing Store Area).
2. Do a spatial join of the point layer with polygon layer (i.e. point layer within polygon layer) with point layer as first input.
3. Open attribute table of join result layer and export this as csv file
4. Open this csv in Microsoft Office Excel Program and select a blank cell besides the fourth column (here we select cell E2), enter formula =IF(B1<>B2,D2,E1 & "," & D2) into the formula bar [Column reference will differ based on your fields], and then press the Enter key. You get concatenated values of polygon info (Store Name) for Point data (Customer Name).
Hope this helps!
-- Thanks, Neena