No engagement on support case and sneakily being resolved

Seeking for advice on what we can do next. We're on developer support plan. A support case was raised in Dec 21 and took months to confirm that there was a technical product issue in Jan 22 and subsequent action taken in Feb ended up corrupted our service. This took more weeks with back and forth and we finally give up pursuing a fix and instead recreating & migrating our service and asked for refund. This was acknowledge in the case then, but since then, a few follows up was made on the case regarding refund processing but nothing was done. The last update I received was on April with all the promises but nothing was delivered and despite more follow ups, nothing was done and nor update was provided. Today I discovered that the case was marked as resolved with no response/action. I just reopened the ticket and asking for explanation. This whole process/ordeal is obviously very frustrating and I'm just wondering if anyone has similar experience and recommendation on what action I can take next. Thanks in advance!