Frustrated

I have an account with jet that's now under rcs, I got a call saying I'm owing for 3 months and I not owing, I even send the proof of payments but I'm still getting annoying calls and emails... Its clear that people are not doing their jobs as I've been calling and even went to the store but they haven't resolved the issue and now it's affecting my credit score as it has dropped by 64.. And I'm already flagged a bad debt I can't even qualify for a loan that I really need 😞😞