EXCEL scramble data

I work in data cleansing and I am looking to build a library of excel files to use for future training sessions from data sets provided by clients.

However due to data protection laws I need some way to totally scramble the data, so I was wondering if there is someway to highlight an area of data and have a macro randomly replace characters and numbers either totally randomly or for example all letter A's replaced with the letter F all letter B's replaced with the letter Q etc and the same with numbers not that bothered by special characters.