How to escalate support?

Hello,

I have had an ongoing issue with my xbox one controller (intermittent disconnections). 18th of April I called xbox support. After spending over an hour on the phone with support troubleshooting (including wiping and re-setting my xbox) I was told to see
if the problem occurs again, and if so the controller would be replaced. I asked for confirmation (and provided the serial number) and was told 100% a replacement would be given.

The issues with the controller were not fixed and so I contacted support for replacement. After going through the whole issue again they took my details (address, etc.) and told me I would receive details within 24 hours. A week later I had not heard from
them and so I contacted them again, this time I was told that they are still working on it, and I would hear back within 24 hours (I didn't).

As of now (12th of September), I have contacted support 5 times, and every single time (except for the first support call) I was told they would get back to me within 24 hours, however not once have they ever got back to me. On the last call, they re-checked
the serial and told me that in fact it was not covered by warranty (even though I had been assured multiple times in prior calls it was). If this is the case it is a bit disappointing, but why would they not tell me that at the start instead of dragging this
out over 3 months and around 4~5 hours of my time on calls/chat with support?

What can I do to escalate this, it seems very obvious that if the support person can't or doesn't want to help they just say "we will get back to you within 24 hours" but never do.

:)