PayPal Credit Paid off with credit card?

Description

Hello,
I have 900£ of paypal credit that I want to get rid of. My plan was to pay the 900£ with my credit card (Barclaycard) and transfer that to a 0% balance transfer card and pay it back within 6 months interest free – I already have the balance transfer card.
Now, when I go to the payment method for the paypal credit, I can only pay by bank account? I am unable to pay by my credit card which makes the transfer impossible.
Has anyone else encountered this issue before? Is there any way around it or will I just have to pay the 900£ back from my bank account?
I asked Paypal but they were no help.
Thank you!