Originally, my return was $1000 and I have yet to receive it. I was told to add my 1095, but when I did, I owed $300. If I pay it will I receive my original refund?

I filed my taxes over a month ago and my return was $1000. I was told to add my 1095, but after I amended it, I owed $300. I realize this is the difference I owe, but I am afraid to pay it since I have yet to receive my original refund. Should I wait until I receive my refund or do I need to pay this difference for them to issue it?