MAHNBESCHEID -KLARNA COEO INKASSO

I bought vitamins from Bulkpowders in July last year- 28 Euro.
There was some problem with the two products and I asked them to reship one and canceled the other product.I wrote to bulk orders to sent me their paypal details to transfer money,tried calling them.They told contact klarna.
While this reshipping/caling order was happening klarna trasnfered to coeo. They started claiming 86 euro instead of 24 Euro( after deleting one product).

I didn't respond to any mail.I contacted bulkpowders again and they had no response.

Now I am getting a Mahnbescheid.What is the best way to deal with this?
I called klarna today and they told that they had already sold the invoice to coeo.I still haven't made the payment of 24 Euro.
I called coeo and they want to charge me 170 euro and won't take 24 euro.
What should I do ?