Yes, DP is still struggling on, and i sometimes wonder if it is worth it, but he needs to do this and make it work. Its almost like, well it can't get any worse, we have been to HELL and are not quite back yet so to just walk away would be the most sensible thing he could ever do, but it would break his heart as this is all he has ever wanted. And yes, we have been there and said that enoughs enough and 12 months later its still shit - thankfully i am going to go back to work when DD starts school and it will help, but christ alive, its been shit.
Do persevere with the national debt line, they can, in some circumstances, act on your behalf. Do you have personal debts too? We do, and DP is not limited company - we are in mortgage arrears etc, its not fun. BUT we are getting there with the help of the debt line. They are an absolute godsend, the only thing i would say is you have to ring and ring and ring, takes ages to get through, hours! Because we are not the only ones suffering.
Now, it probably wont come to this but a word about bailiffs. DO NOT LET THEM IN YOUR HOUSE. You are not obliged to let them in - but if you do, they can list your goods and chattels and could seize them at a later date. We have been down this road, thankfully they didnt go that far and have actually been really understanding. Those are the scary council tax guys too.
Credit companies etc, debt collection agencies have limited powers.
I know this is not my business, but if you are struggling with personal payments, credit cards etc, write to them and offer reduced payments - you have to provide a budget sheet showing incomings and outgoings. Also, you can ask them to freeze the interest. That way, you can possibly free up more money to pay priority debts which the HMRC is. There are sample letters on the national debtline website. They pretty much saved my life you know, as serious as that.
Good luck with it all.