Lee spring

Hoping someone can help please? My cis has been paid into my old utr account all year. I have certificates to say where the money has been paid but cannot reach an advisor to help. My UTR was changed may 23 due to an error by hmrc but for some reason my payment continued to go into the old number which now it seems noone can access and I'm set to lose £4100 tax repayment. Who can I approach for help? Whenever I ring self assessment they just give the usual response " wait 12 weeks for security checks" then the 12 weeks are up they say it again. I know this as I had it for 18months with my last tax return repayment! Online chat doesn't seem to be working at all this year either!