Poor service

I have an with account with Jet clothing. I took a Samsung cellphone from jet in 2020. I have been debited monthly Instalments for the phone and R50 Jet Funeral Cover since 2020. I went to Klerksdorp Jet store in June 2024 to cancel the account because I thought I was done paying for the phone. I never received any Cell C airtime Jet was claiming they sent me. I was told the remaining amount owed is R5000 and more additional to the money debited already. I do not understand where such a huge amount of money is coming from. I’ve paid up over R5000. I want to cancel the account and I was asked why am I closing the account. Every time I call to get the matter escalated I can’t get a hold of any superior.