In MY opinion, you get nowhere by CONTINUEING to be polite. I would play merry hell if they took this attitude and I really needed the courtesy car having told them that I was prepared to wait until one is available.
If it is a recall, you are entled to a replacement while they do whatever they have determined is necessary to rectify their FAULTY parts/labour. I would make a point of insisting on their fulfilling this obligation, even if I didn't need a car, if this is their attitude.
The work has to be carried out when it suits you or you can hold them responsible for any safety issue.
Regarding the response from
, I suspect that what I suggested in other posts, i.e. that the first contact response is always a "Sorry, but NO", is becoming more and more perceptible with every new complaint. Look for contacts at a higher level (elsewhere on these pages) and complain via email or phone.
I disagree that trading standards cannot or will not help you. If this is a safety issue, I would even email VOSA.
Please do let us know how this turns out.