Napa Auto Parts They refused to take a core back. Canyon Lake Texas

I bought a brake caliper online (From Napa Auto Parts) and had it shipped to Napa Auto Parts in Canyon Lake, Tx.  The caliper had an $83 core charge.  I returned the core but I had foregotten the reciept, so I went home and printed a copy of the online reciept.  I returned to the store only to have the clerk tell me that he did not know how to return the core charge from an online purchase.  The clerk called his boss and he also did not know how to return the core charge. 

They took my phone number and said they would call me when they worked it out.  I didn't hear from them so I went into the store the next day and got the same run around. Ditto the next day.  Then I made an online complaint with Napa and received a response saying they took my complaint seriously and I would be contacted in 48 hours.  I waited 5 days and made another complaint with the same result.  Obviously they had no intention of refunding the core charge.  Very dishonest company.