NCO National Financial. Will not provide email address on website and contacted place of employment, not me directly Attempting to continue to claim debt after should have been resolved. Horsham Pennsylvania

After my department made about three thousand dollars in payment, then I made over a year worth of payments that were deducted from my bank account, they garnished 12,000 dollars from my employer.  They took my income tax return of almost two thousand dollars and are now attempting to garnish me again me again for eight thousand eight hundred and thirty four dollars and some change.  How can you garnish and take and say I keep owing you money.  I mailed a letter requesting an exact amount of monies owed and monies paid in, but have not received any paperwork showing the exact figures.  I feel as though I am being scamed by this company as well as Kaplan university and student aid.  Right now we are looking at over twenty five thousand dollars in paid to this account and I still do not havce a diploma???