No animal on fluid therapy should be left alone for the following reasons:
Hydration status cannot be monitored and the animal can become overhydrated. This can be fatal. Especially for a cat.
The IV pump could alarm and stop (and usually does) meaning the patient will not receive the fluids it needs.
The patient can become restless and disconnect their IV line or pull out their IV catheter leaving an open port directly into their vein for bacteria.
Most vets will have signs posted stating that there is no night attendant on duty. I believe this is also required by law. Honest vets will tell you outright that your pet will not be monitored overnight and explain the risks stated above. They will also suggest that you take your pet to a 24 hour emergency facility for monitoring while on fluids. Further, they will have you sign an AMA if you refuse to transfer your pet. Less honest vets will withhold that information and continue charging you for hospitalization.
I have seen pets die in their cages overnight because they didn't get the fluids they needed.
Any cat not eating should be at least syringe fed to avoid hepatic lipidosis. If your cat was truly not given food for such extended periods, there had better be a legitimate reason why. It is otherwise malpractice.
There should be DVM notes for every day that she was there. If not, that is malpractice.
"N0 one had told him (The weekend vet) he should look at Lakshmi."
Oh, that's BAD! Total malpractice. He is personally responsible for every single patient in that hospital. In no way can he blame staff for his neglect.
"Lakshmi did not eat food when offered. My feeing was it was because of under-treated pain."
Dr. Abdelmalak said the three sets of X-rays were very difficult to read and understand because they showed poor organ definition.
Or because they were crap x-rays taken by crap staff with a crap machine. I would have to see them.
You have some very good and very pursuable points on how Lakshmi was neglected. I would stick with that. If you want VV investigated, you need to get a copy of your records and file a complaint with the VMB.