I'd correct both of them. Remove the excess plus investment experience and put it in the suspense account. Then use it to offset the next matching deposit(s). I would not send it back tot he company as mistake of fact..
It's my understanding that the required 20% is the minimum and you can always request more. Given that most participants (particularly those under age 59 1/2) will owe more than 20%, it seems perfectly reasonable.
Do you like paying high fees/commissions? I guess you do otherwise you would not be fixated on the high fees/commission based 403(b) maintained by your wife at AXA. Have you digested my prior post? What other k-12 districts allow should not be an issue for you at this time----you must deal with your options and your options are either to pay tax on the distribution or roll it over to an IRA with Vanguard. For me this is a no-brainer!!!
Joel