That might have been a tad condescending

The shock absorber does two things.
Firstly it limits the travel of the trailing arm to about 80% of its range of movement. Without this limit, a decent bump will see the spring escaping, followed by lots of carnage, both for you and other road users...
Secondly it controls spring bounce, by damping the spring reactions to bumps and dips and therefore keeping the wheel in constant contact with the ground.
A failed shock will knock like a bastid, and not provide the second function, so the wheel will behave like a rubber ball, bouncing enough to leave the ground. This would probably make the car near undriveable, but importantly it would still provide the first function.
If the shock mounting has failed, then it
might provide damping at the limit of the compression stroke but only when the top mounting stops moving up, whether that is at the inner wheel arch or parcel shelf. However, it won't control the down swing of the trailing arm, so potentially could allow the spring to escape or the wheel to bounce on anything but glass smooth surfaces.
Personally I suggest the following... get the RAC out. If the shock is secure but failed, you could consider driving it to yours, but would be illadvised to do so, knowing it is defective.
If the shock is unsecure, get it recovered to you. No ifs or buts. If it's just failed mounting rubbers, the mounting kit is available from VX for reasonable money, then renew the shocks and mountings both sides. If it's the metalwork that is the issue then strip the wheel arch in and out to properly asses the damage and go from there
