Terrible customer experience

I contacted them as I am in the process of applying for a job. I had to take my current job with a lower salary and could not maintain my credit card payments. Now I am trying to get a job with a higher salary and all I need from them is a letter confirming I have a payment arrangement in place. When I called them they said they could not provide one, but yet I have an email which states confirmation of payment arrangement. All I need is the same thing but in a letter so I can get this job and actually start paying this debt off with proper payments, yet they won't assist me. I just need something confirming that there is a plan in place.