Navient Student Loan Complaint

Navient Student loan department,

Non-federal student loan Dealing with my lender or servicer Trouble with how payments are handled California

I received a private loan from - - in 2010 for my undergraduate studies at - - -. Upon graduation, I attended - school at -. I eventually deferred my loan repayments ( which took months ). I recently found out that Navient took over my loan repayments ( - - did not inform me ). Since last week, my mother ( co-signer ) and I have been receiving calls from Navient, not during business hours, about paying. I logged into my Navient account for the first time today and it said I defaulted of my -/-/- payment which was supposed to be deferred since I am still in - school. Now i have to re-apply for deferment which I fear may take months and may negatively affect my credit score.