How to manipulate the receipt variables?

I am modifying the account statement receipt template. There is a variable AccountStatement.Activities.Description that gives something like: Store Name - New Charge -- Transaction #77
I am interested in breaking down this 'atomic' piece of data to remove/edit parts of it. I tried to use vb string functions such as substring but the renderer does not like it. Is there a trick I am not aware of?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a site by and for consumers of financial services and advice. We are not affiliated with any of the banks, financial services or software manufacturers discussed here. All logos and trade names are the property of their respective owners.

Tax and financial advice you come across on this site is freely given by your peers and professionals on their own time and out of the kindness of their hearts. We can guarantee neither accuracy of such advice nor its applicability for your situation. Simply put, you are fully responsible for the results of using information from this site in real life situations.