I see vanco ordered in 250 ml at 250 pretty commonly. You don't mention the dose of Vanco so it may or may not be inappropriate to run it in over an hour, you would never run it in less than hour. Are we talking 500 mg, 1g, 1.5g? Giving each of those over an hour is a different picture depending on the dose and the patient.

Also, most vanco is managed by our pharmacy. The nurses actions may or may not have been inappropriate, it's possible she consulted pharmacy first for example. That said, it sounds like the patient had the peripheral IV for quite a few days already, based off the meds is seems like he was getting I would not be surprised for it to be irritated by day 4. For our hospital policy he would be getting a new IV irritated or not by 96 hours regardless. I wasn't there, but more likely than not, the phlebitis is related to the length of time the IV has been in and the types of medications being given for the past 3 days.

Patients can and often do make decisions that are contrary to what is best for them. If they do not hold the power for making that decision (for example refusing a medication outright), it's your responsibility as the nurse to call the appropriate people to let them know what decision the patient wants to make and work it out. If they want a new IV rate, explain that to whoever is managing it: if it can be safely given get an order to do it that way, if it can't, the ordering provider can write to hold the med, start a different med, etc.

It doesn't seem like you have all the information though, I would let your clinical instructor or the nurse you are assigned to (that got report on the patient) know your concern, or you can call the patient safety hotline if you're really worried. The day shift RN probably has a more complete picture of the full details of the situation.