How can I cancel my contract because the product is useless?

1. Hi.

I bought the Adobe ExportPDF to convert PDF Files into Word format. Unfortunately the product does not really convert the documents properly into a word document. After converting the documents, containing mathematic formulas, those are not properly converted. So the product does not provide the service as promised.

Therefore I's like to cancel my order for the Adobe ExportPDF.

Additionally there is absolute no help what so ever to cancel orders at the internet page.