california DMV Unlawful Vehicle Fee Sacremento California

The CA DMV Dishonored Check Unit sent me a bill for 700$ for a car I sold 4 years ago.

In May of 2013 someone walked into a DMV office and wrote a check to register a Honda Civic I sold to  private party in 2009. The check bounced and the state of California sent me a bill for 700$ , coverering vehicle registration, late fess and penalties. The DMV tells me that the bad check does not belong to me but due to legal reasons they cannot show me the check.

I went to the state website and printed out the vehicle report. The California vehicle report states that I sold the vehicle in Dec 2009 and that the vehicle was transfered to the new owner in Jan 2010.

I sent a letter to the CA DMV Dishonored Check Unit that included the vehicle report. The letter pointed out that the vehicle was no longer owned by me ( I underlined the appropriate lines in the DMV vehicle report ). I also pointed out , by their own records, the bounced check was not written in my name.

The state sent me a letter dated 8/26/2013  saying that I still owed 700$ and the fee was due 9/3/2013. California theatens civil action which could affect my credit rating.

The question I've asked at two DMV offices is  : Should I pay 700$ what garuntee do I have that in May of 2014 the same thing does not happen. Someone walks into a DMV office, writes a bogus check and DMV sends me the bill ? The anwser from both offices is resubmit my paperwork and wait !

Help, help because I value my credit rating I will pay (reluctantly) the 700$. I do not whish to go through the process again.  Any suggestions .... please