Failing bowel prep - nest steps please?

Hi, I'm sorry to bother you but I don't know who else to ask! My daughter is only 24, so appreciate the chances of her having bowel cancer is slim. We have been ignored about how severe her constipation is for years. She had a colonoscopy in 2019 where they removed polyps but couldn't get past a certain area to check anywhere else. There was no follow up, she had had ongoing pain and constipation, usually passing a stool every 10 days. She has now been very poorly for 4 months.... Feeling faint , lost over 2 stone in weight Her last bowel movement was 4 weeks ago and 2 months prior to that she did 4 motions of only 1 rabbit dropping and a pan full of blood. She has not been able to keep any food down for 5 weeks, she just brings it back up. We have pushed for a ct scan but hospital refuses. They are going to do a colonoscopy and endoscopy tomorrow ( we had to push for this too!? ) She is on double bowel prep as I highlighted the previous inability to get round a certain area, and that it doesn't usually work for her. She has taken 2 lots... One at 7pm last night, one at 7 am this morning. She has had no stool movement at all...she has passed a very small amount of liquid bowel prep and nothing else. Her tummy is making noises. My question is ..... Has this happened to anyone else and also if it doesn't work at all and they can't do the colonoscopy what are the next options. I'm desperate and sad for her !