Rossendales hassling me for a 250 approx CT debt.

I supplied them, through email docs, proof I'm on benefits and can only afford 10 a month.

I set a standing order up and it's been paying a short while.
They wrote to say according to my income I have to pay out more than I'm receiving which isn't possible therefore I must pay 50 a month LMAO!!!!
Loving the logic there.

I found a hand delivered letter today which state I now owe 450 (WHAT??!?!) and that they wanna take goods blah blah.

I've been paying 10 so will I still HAVE TO pay the extra they've slapped on?
What do I do?
Just make sure no one answers the door and...? Will they keep visiting and slapping another chuff knows how much on the bill?

I've shown proof it can't be paid, have no money on benefits, surely this is illegal? Wish I could take them to court I'm sure a judge would see it as bullying.

Incidentally the original issue didnt reach me for years (from 2012) becuase I'd moved on, wasn't registered anywhere and council claim I owe overpaymenticon of benefits, you know that old chestnut. Irrelevant now.