Couple of thoughts:
1. When you go to the Cakewalk Store, are you selecting the correct Region?
2. Did you check your email for any download links? (Perhaps spam folder as well), and is the email address connected to your Cakewalk account a valid email address?
3. While it may not be convenient or cost-effective to phone technical support, with you being in the UK, you DO have enough posts to allow you sending Private Messages to folks like Noel, Bothwick or Ryan Munnis. They have been VERY helpful to the small number of folks who have asked them for assistance in resolving registration/download issues. This may be your best bet, if the first couple of thoughts I listed above do not resolve things for you.
I am not at all sure why you seem bitter/disappointed (or something else) with regard to your past experiences with Sonar and/or Cakewalk - and I do not need to know. I would suggest that by all accounts, both here in the forum and out on the web, Sonar X3e (particularly Producer Edition) is being regarded as one of, if not THE, best released version of Sonar - perhaps ever.
X3e does not have any 'show stopper' crashes that I am aware of, and has a rich, useful, and powerful set of features and add-ons.
For any issues/questions that arise, the forum has been extremely cooperative and thorough in helping folks get things figured out.
Lastly, per some posted content from the Cakewalk folks, the largest set of reported issues with X3e are actually problems with 3rd-party plugins, and not with Sonar itself, so please consider that prior to jumping to any conclusions with regard to the stability of X3e.
I hope this works for you,
Bob Bone