CenterPoint Energy complaint: Sold my house, centerpoint added new charges two years later

I sold this house to my tenant on 6/23/2021. At this time the account was up to date. The last time I needed to make a payment when the tenant was late was 2/12/2020. On 2/12/2023 they sent me a refund of 128.73. (Sort of late if you ask me.)

On 8/9/2023 I received a bill (even though their web site says this account is inactive) for 173.42. This itemization was 1.42 for service, 112.00 for deposit, 60.00 reconnect charge. The following should be clear: I would not be establishing a new account for an property I sold two years ago.

The buyers (who had been my tenants for several years) claim that they paid the company on August 9, 2023. Is this a duplicate bill? I don’t know. I do know these charges are not mine.

I discussed this by phone with the company on August 18, 2023. The account rep (Lisa) seemed to agree that these are not my charges. She promised to call me back but never did.

The current owners contacted the company also on the same day and were promised a return call too which never arrived.

I have submitted three requests via the company website. Again, no responses.

This bill will be late after August 26, 2023. I suppose the company will report my non-payment to the credit agencies. I have a score over 825 and do not want them to hurt me.

Please help.