the Immigration Office has nothing to do with the issuance of visas, the MFA administers this via their foreign missions. I would approach the embassy/consulate in your country directly.
are you high? It works perfectly alright. Clear case of user error. This IS the website you’re supposed to use for everyone under the jurosdiction of the RTE London.
you can not apply as a freelancer who has no track record of operating a real business or income from your business source to prove you’re working (usually proof of income isn’t required with a business registration). Otherwise everybody could do it and just come up with some unverifiable story. It’s easy to get a DTV but not THAT easy. 😬