Charged twice for last month’s broadband bill and no clear credit showing

Hi all, hoping someone from Nexora can explain this because I’m getting nowhere with the app. I paid my broadband bill on the 2nd, then this month I’ve been charged again for what looks like the same amount plus a random £6.50 “adjustment”. My statement just says balance carried forward but I can’t see what it’s actually for. I’m on account NX-447219 and the address is 18 Ashfield Road, Leeds, LS7 3QJ. If it’s a billing correction, fine, but why not show it properly? I’ve had no late payment emails either. I’m worried I’ve been overcharged.