RCS *****

I have been paying RCS for many years. Haven't used the account more than 7 years ago. My amount owe suddenly shows more than what it was. How is that possible? For some reason I dont receive any statements on my *** anymore? I get calls that they want my account details as my installments are now higher. I want this to be investigated and want to get statements to show where I have purchased anything that I still need to pay this account. Something isnt right and I think after atkeast 7 to 8 years of installents it should have been done already. You can't call them because the phone numbers are just ringing. You can't email them, they just simply ignore it. I want to get rid of them as fast as possible so I don't need to deal with this ***** anymore.