£220 is not a fixed penalty. It is exactly the fine you would expect for a Band A offence (see
Mags' Sentencing Guidelines) with no discount for a guilty plea (e.g. SJPN ignored) and an assumed RWI of £440 (no statement of means submitted).
This is consistent (but not conclusive) with someone naming (and purporting to be) you in response to a NIP addressed to you, and then burying their head in the sand when an SJPN arrived in your name.
Absent compelling reasons to the contrary, speeding cases should be heard at the court nearest to the offence, or a "linked court". Not sure whether the SJPN process would be an exception to this (it is not a conventional hearing).
Unless the DVLA have managed to outdo themselves on this occasion, an order for endorsement under your name (whether purporting to be you or someone else with the same name) came from Nottinghamshire Magistrates' Court on April 20th. Other than similarly not being fit for purpose, it is inexplicable (and/or unacceptable) that they are unable to find any record of that.
*If* the court are that incompetent, what can we be sure of?
Logically, either the court have f*cked up, or the DVLA have. Have you asked the DVLA webchat people if they have access to the instruction from the court? Did it have your correct and full name, date of birth and driver number?
Going back to the spite angle, would your ex have had access to the property when a NIP would have arrived (within 14 days of the date of offence if it was your vehicle and you are/were the RK with up to date details)? Unless paperwork sent to you as RK was intercepted, there is every reason to believe that your vehicle was not involved in the offence.