Sorry to hear Paul that your car didn't pass ....can't believe though that you got an advisory for a road legal tyre. Beggars belief, so I think you are right to walk away especially as they don't care about having your custom in so much that they couldn't "squeeze" you in to do the repair ...after all it's not a big job.
Lets hope you can get if fixed and enjoy the car again. Have a great day tomorrow and sorry I can't be there.