On some new/we cars, if you DECELERATE too quickly (IE, coming off a motorway), the emu will kick in, and out you in limp mode. This is enough to get you home. It was designed to protect the gearbox. I think even a lot dropped it.
Not sure on how to reset. You can buy (from big autoparts) a "thingy" that plugs in your internal slot (drivers side, often by the fuses) used for getting n sorting chip issues.
You plug it in, and BT to your phone, and via a particular app, it'll tell you what's wrong, and what's needed to fix.
Several versions around (I think AA sell one) on internet.
if you have HOMESTART etc, call them out tomorrow and explain what happened.... They'll prob plug their own "thingy" in.
This is what I meant.... Loads to choose from ...
Autel OBD2 Reader Diaglink, DIY Version of MD802 All System Diagnostic Tool for All Electronic Modules (Engine, Gearbox, ABS(under Scan), Airbag, and More), EPB, Oil Service Reset https://www.amazon.co.uk/dp/B01N0QQZY7/ref=cm_sw_r_other_apa_i_E6NhCb4DCM1JX