Yes, its possible.
1. Select the cells which you want to be unlocked ( in this case, cells related to "amounts and the customer’s information")
2. From Menu Bar, select
Format > Cells... > Protection Tab
3. Uncheck (click to remove the tick mark) "Locked" checkbox and click "OK"
4. From Menu Bar, select
Tools > Protection > Protect Sheet...
5. Type in a password (and remember it since there is no way to retrieve in case you forget)
6. Re-Type the password as shall be prompted by Excel after pressing OK
7. Your Excel file is protected now, and one can only input in the unlocked cells, as desired.
[N.B. You can refine your protection criteria by playing through he options you get at step 5]
Regards,
Argha Bagchi