I had a contract phone that I took 2023 June according to me I fished to pay them but they are still busy sending invoices that I owe them

I had a contract phone that I took 2023 June according to me I fished to pay them but they are still busy sending invoices that I owe them.I tried to call them and also went to store but no assistance on my issue .The cancellation department does not answer calls to resolve this issue.I will appreciate your assistance in this matter . Thank you