i hope this dosen’t come accross in the wrong way.
take a deep breath, sit down and write out your case as you have stated, calmly explain as you have above why you have come to the conclusions you have and ask them to reconsider the vehicle you think fits your needs and why. i know its difficult not to get stressed and emotional we’ve all been there at times.
you’ve nothing to lose the worst they can say is no.
but take your time and maybe get someone to look it over for you before you send it.
i would always do this in writing rather than over the phone as if like me you can get flusstered or side tracked.
good luck
never accept their first answer—unless its better than you asked for!