Being ignored on seller support "work in progress"

Anyone got any advice on how to get Amazon seller support to reply to a case?

I raised a case at the end of December, the last reply I had was 21 January, status is "Work in progress" I've sent endless requests for an update but just ignored, I've called and they have set up a new case but then merged with the original one.

The case is about a removal order which shouldn't of happened as the product was in date, I'm trying to get a refund on the removal fees and units which were damaged / missing from the removal order. Any advice on how I can get Amazon to respond?

Thanks

Kate