Cannot resolve BRP error issue for 17 months

Hi All,

Help needed to resolve a simple BRP error that I cannot resolve through standard UKVI process for 17 months now.

I'm on a 5-year family member route.
Leave to remain was granted in March 2020 with the confirmation letter stating it is granted for 30 months.
BRP card states 24 months.
Actions taken:
1. Error reported immediately, within a month receieved a confirmation from BRP Error team that the case was forwarded to the caseworker for review and nothing. After following up with the BRP Error team and sending a request to the caseworker by post (to PO Box), in August 2020 receieved an email from the caseworker that my case is under review. Success!
2. Nothing until Feb 2021 with my attempts to follow up with the case worker and BRP Error team.
3. Wrote to ukvigeneral@mailgb.custhelp.com who responded advising to report the error again, which was done.
4. Nothing till May - I reached out to the local MP asking for help. In June they receieved a hold response from UKVI.
5. Early August 2021 followed up via all available channels: BRP Error Team email, caseworker email and post, general customer help email (no longer valid providing phone number now - 2 attempts to call, 30 mins wait time with no response), MP who promised they escalate the case.

This is an embarracement IMHO but what do I do next?
I have no hope that continuing with the same approach will bring any result. Any advice?