Yes. It needs to be processed through a formal returns procedure. If you find you cannot get any joy that way, send it recorded delivery to the head office, with a letter of explanation attached (in an envelope) to the OUTSIDE of the packaging, and a separate copy of the same letter (also by recorded delivery) in letter post.
In the letter, don't only explain what the problem is but also what you expect them to do about it - but be reasonable and within your rights.
"Please find enclosed FVP-4000T serial number xxxx. This item was purchased direct from you on invoice xxxx dated xxxx. I have been unable to obtain satisfaction through your formal support channels.
"I am returning the item to you, with proof of delivery, because it does not function in the manner described or for the purpose to which it was purchased. As such, it is not fit for purpose, and I am claiming a refund in accordance with your legal obligations under the Consumer Rights Act 2015.
"Kindly forward a refund of £xxxx to me at the above address within 14 days of the date of this letter."
Something like that.