Reimbursement for buyout costs after switching from Verizon to Xfinity mobile

Xfinity has been very difficult to work with when it comes to getting any answers regarding the reimbursement for the buyout costs switching from Verizon to Xfinity mobile. Verizon will not send me my final bill until July 28th, but Xfinity is saying I only have until the 25th to submit the correct documents in order to qualify. I called Verizon and told them I needed some type of bill to turn in to be able to qualify in time for the reimbursement in time. Because I switched my mobile number over to Xfinity Mobile, I no longer have access to a Verizon account, And they do not have a bill with my number attached to it until I receive my final bill on the 28th. I have tried everything including using the disconnected account sign in It did not have the information I needed. I need to have an exception until my final bill comes in or I need Xfinity to accept what Verizon sent me, which was a copy of what the final bill should look like but with the agreement numbers attached instead of the phone numbers that I moved over to Xfinity Mobile. Please help.