Someone told my I'd posted in the wrong place, so I've followed their link and posted again. I apologise if this is now in exactly the same place again, but that's where the link took me.
Sony Vegas Movie Studio 17
When installing the product it asked for an e-mail address. I added my hotmail e-mail address. It then demanded afterwards that I register the product and create a password, so I used the same e-mail address only for it to tell me that this e-mail address was already being used. I tried to recover the password (that I never created in the first place) and I received no e-mail so I had no choice but to use a different e-mail address (my gmail one) to then create a password and register the product. Now the program won't work because it says the product code is registered with a 'different e-mail address'.
I am unclear if the issue was caused by this or whether the disk I got from amazon has a copied product code and that I've been scammed.
I definitely used a product code, not a voucher to redeem.