MRS BPO, L.L.C. Debt Collection Complaint

MRS BPO, L.L.C. Debt collection department,

Credit card Cont'd attempts collect debt not owed Debt was paid New Jersey

I paid this company $1400.00 on - -, 2013 to settle a collection account with - but - is stating they never received payment for this account. I need a letter stating this account was paid off so that I can forward it to - because it is hurting my credit score.