Worst service ever

Good day Ive been under debit review for 5 years with NPDA. I finished paying on Janaury 2020, but NPDA is still debit money from my account and still refusing to give paid letter and last 4 proof of payments that I made to them, as I need them? Ive called more 100 times between Jan and March, but there's still nothing been done. Can you please help me as I tried everything in my power to get them to help me.