Paypal abd Barclaycard fraud

Can anyone help with some advice please.

I have a Barclaycard linked to my paypal account.

I decided to close this and paid off the balance. Barclaycard then wrote to me saying I owed a small amount of interest on the closed account. I spoke to them, they said they would open the account, I should pay of the balance and they would close the account again. (This was a conversation on the phone). I paid off the balance and thought everything was OK.

This month I received a bill on this account for £6000. I immediately called Barclaycard and they told me it was a Paypal charge and I should contact them.

I spoke to Paypal and they said it was a charge for digital goods and had been purchased legitimately using my username and password.

I have now raised cases with both Barclaycard and Paypal and neither of them will back down and say I must pay the bill.

What do I do? It is now obvious that my Paypal account was accessed fraudulently.

Who can I turn to for help?