This just says what they already told you:
“Should the third-party provider fail to correct the issue
and agrees to refund us, we will then refund the Customer”.
I'm pretty sure that condition won't hold up where I live. The seller is your main point of contact, and any problems should be solved by the seller. Bitrefill operates
under the laws of Sweden. I have no idea whether or not this condition is allowed under Swedish law, but I find this a very bad condition. It means Bitrefill won't take responsibility for the products they sell.