I experienced a similar problem but was not an Ez-pass holder. I was missinformed and believed erroneously that Delaware was using toll by plate.

I did have it forgiven. I quickly got a PA EZ-Pass and sent a check for the $4 and a copy of my account balance on the EZ-pass, but I whited out the opening date. PA puts another date at the bottom of the form that corresponds to your toll-by-plate customer date. Delaware sent me a nice letter saying I was forgiven. Thank fucking GOD!