OP, you were asked earlier to 'Please post up a picture or scan of the letter you received. Obscure or readact your name and address, please leave everything else visible. Instructions are in Read This First sticky post at the to of the forum.'
I cannot see that you have, but you should.
Posters' calculations suggest that this letter was notification of 2 Enforcement Fees(@£235). This would have been preceded by 2 Notices of Enforcement from the same enforcement agents. These would have been posted and therefore it's all NTOs, CCs, OfRs and Notices of Enforcement which haven't been delivered. In the world of probability this is at the extreme.
As active warrants are in effect - debates about whether they're 'defective' or not won't change what happens next - then all you can do is to pay and/or submit OOTs. As payment does not affect your right to submit OOTs nor TEC's responses but at least caps what you would pay, then I would give serious consideration to doing so. Afterwards you could try chipping away at the agents' fees and of course if OOTs are successful then these would be refunded.