Read this if you planned to go to a fast-track app with a cancellation letter

I booked a fast track 2 weeks ago and planned to take a withdrawal letter for the current online application to the appointment like i had seen other have been doing. Ive posted 2 withdrawal letters to the office who has my daughters birth certificate and heard nothing. Started seeing horror stories of people being turned away yesterday and spoke to an adviser on chat who started the cancellation process off for me and said once it's cancelled I will be contacted. Called this morning and had a horrible rude man talking down to me saying that I will just be turned away and the chat adviser shouldn't have started the cancellation as now we can't attend the fast track or proceed with the original application. He just kept telling me over again I will just be turned away and now all I can do is wait until its cancelled which in his words said it will be weeks and weeks until they action it. He then proceeded to say he doesn't know why I'm wasting his time and put the phone down on me. I just can't believe this is happening. We officially can't go on holiday on the 13th of May now. I'm just in shock. So please be aware they aren't allowing this anymore it's best to just stick with the original application and hope for the best!