Nothing beats speaking to someone on the phone, but I have had incredible luck with the RMV "contact us" form. I've received an email back within a few hours with all the info clearly spelled out... and it was an actual person, so then I could email back and forth. They even offered to speak to me on the phone.

Put your story with all your details in the "contact us" form... and keep trying to call the 1800 number.

https://www.mass.gov/forms/rmv-customer-contact-us

Good luck!