Yeah, you're missing a lot of paperwork here. That makes it hard to give you good advice, because timing is crucial here.
If you don't pay a Penalty Charge Notice on time, they send you a letter called a Charge Certificate that increases the amount you owe by 50%.
You say that you paid them the £70 that was due. The council are saying it had gone up by that point, and you actually owed £105.
If you pay less than the amount that's due, the council are allowed to keep it as part-payment and chase you for the rest.
They registered a debt of £44 against you. That's the £35 they're saying you still owe, plus the £9 court registration fee.
The bailiffs got involved, and sent you a letter. That adds £75 onto the amount owed. That almost triples it, taking the total to £119.
The bailiffs had to come knocking on your door. That adds £235 in enforcement costs to the amount owed, tripling it again and taking it to £354.
If they visit you again and actually take steps to remove goods (your car), it will add another £110 on, taking you to £464.
They're saying that this is justified, because you missed the deadline to pay £70 by one day. We can't tell you if they're right or wrong, because we'd need to know the date of service on the Notice to Owner and the Charge Certificate - two pieces of paperwork that you don't have.
In fact, you seem to be missing a lot of paperwork. In addition to the Notice to Owner and Charge Certificate from the council, you should have an Order for Recovery from a court in Northampton and a Notice of Enforcement from the bailiffs as well. Sometimes post goes wrong and people don't receive one of these letters. But you're missing all of them.
You say your V5C is up-to-date and has the correct address, but when did you update it? The V5C should have a date of issue on the front page. Did you by any chance update it after September last year?
You should stop having back-and-forth emails with the bailiffs. They won't back down and it won't delay them from coming to visit you again. They have been instructed to collect a debt on behalf of a council, and they won't stop until they either get the money, or the council calls them off. Also, they don't need to give you any proof. Penalty Charge Notices are dealt with by a special court in Northampton. Unless you fill out a certain form and post it back by a certain deadline, the court automatically sides with the council and gives them permission to send bailiffs after you. This has already happened to you. The bailiffs have a warrant dated February 2024.
If I were you, I would phone the council. Act confused (but polite). Say you've paid it in full but you're still receiving demands. It's a gamble, it might not work. But you might get through to a nice person who's in a good mood that day and decides paying £70 a day late is good enough and closes the case, calling off the bailiffs. If that doesn't work, ask them to send you copies of the paperwork. You really need the dates for the Notice to Owner, Charge Certificate and Notice of Rejection of Formal Representations (if it exists). The dates on these are crucial in determining whether you owed £70 or £105 at the time in question. They might be able to generate dated PDF copies from their computer system and email them to you. You might have to put in a GDPR Subject Access Request to find out.
Here's the thing - even if it turns out the council were wrong to send bailiffs after you for the extra £35, there's not a lot you can do about it. You'd have to ask the court in Northampton for permission to file your paperwork four months after the deadline. There is a form for that, but it's pretty hard to get it accepted and you only get one shot at it.