Clearense letter

I have been under debt review since 2016.. With First National Debt then I lost my phone and charged my number since then I've been trying to get hold of them since 2017 late till now and it's really affecting my credit score because now their numbers and email addresses are not working.. And I need a clearense letter to clear my name on credit review... What I don't understand is why can't they send me a letter or something