How many have you been through in your life? As a lorry driver, I've been through quite a few.
A vehicle is required to be at a test pass level all the time it is on the public highway.
VOSA can't only "just advise a repair is carried out". They have this little thing called a GV9. It allows them to prohibit use of the vehicle on a public road until it has been through a full MOT at a VOSA test centre (not a normal MOT station) to get the GV9 removed. The prohibition can be in effect from anytime from immediately to the time needed to take it to a place of repair.
Thankyou for confirming you know f*ck all about this.