SoCal Imports Unreasonable return rules Long Beach California

I am restoring a '70 VW Beetle, over the last 5 yrs.  I have collected parts waiting for my VW expert to install.  I ordered a glove box lock w/keys on 9/6.  Parts were not opened or installed until 10/13.  In the box I found  the incorrect glove box lock.  Their return policy, 30 days,  was written on an invoice copy in the box.  As soon as I found out that the wrong part, ( their fault) was sent, I tried to call but they are not open on weekends.  I called as soon as possible today, 10/15, and explained the problem and asked could I get the correct part and return the incorrect one.  No go.  They would be glad to sell me the part they were supposed to send in the first place but they would not take back the wrong part, even with me paying shipping back.  Needless to say, I'm stuck with  the wrong lock and had to go somewhere else to get the correct part.  I think their policy is unreasonable as I offered to pay to ship the wrong part back and I was 9 days past their 30 day policy.  I don't know anyone restoring a car that does not accumulate parts before putting their car together.