Do folks have experience disputing charges paid partially with points?

I booked a flight through the UR portal with 130K points and $500 cash. Flight was cancelled. Chase/Expedia confirmed that I am entitled to a refund, but that it could take a few weeks. It's now been 10 weeks and no refund.

I'd like to initiate a dispute to get both the cash and points back. Does anyone have experience with this? Do I go about it the same way that I would a normal $ dispute?