Incredibly bad service

I have as a private person, not a business received very bad service from Incredible Connection. They want to register for the offered 3 year warrantry on their webpage. They expect you to be able to understand technical things like the USV number is. I paid cash I didn't have an invoice only a receipt. Why should I contact the store for this. Why was the form not filled in in the store before I left? Why was the invoice not emailed to me so I could have an electronic version of it. The store was the Branch in Rosebank