Mtn messing up a 25 year old account and relationship

Just received my latest Mtn Statement. I see they changed the account number, but also messed up my address, they reveted back to my id nr I had 25 years ago, before Id' s changed when ANC took over.. and iI have proof that they took money ( correct amount to the cent) on 30 June 2020 from my Fnb account... but recent statement, show that I did not pay last month. Thank you Mtn 100% what I need after being a loyal client from 1995....