I did that,it got me nowhere.I phoned them up,was advised to put in writing why I had declared my old car SORN late.Yesterday got a letter saying i was deemed liable for the £80 fine.I aint paying it.What can they do?

I forgot to declare my old car SORN which is off the road,it has been for over 2 years (coz its a heap of junk)I've never got round to scrapping it coz I've lost the log book,and I got a letter saying I should either pay a £40 pound fine,or,relicence the car paying any backpay,or,declare it SORN.SO I declared it SORN as they asked,two months late,but I did what they asked.I then got a final notice to pay an £80 fine.Phoned the DVLA and she said it was a fine because i was late declaring SORN. I would' nt mind if I got a fine for taxing it late,but I declared it SORN.If I,d have known that I was going to be fined £80,I would have paid the original £40 fine. I then went on to send the DVLA a letter explaining the situation and thought that the fine should be stopped,they replied, that I am deemed liable for the £80 penalty.I aint paying it!