Incorrect customer captured on an invoice and wrong description on another invoice

[Sthembie]

Could you please assist in advising how do I go about making correction on the invoice that I captured and used incorrect customer.For example instead of Umgeni I captured Eskom.
On the other invoice I selected incorrect description,both were captured on Pastel v11 and only realised after I printed the invoices.

Your assistance would be much appreciated