Not sure what to do with some surgical nurses who refused to help with cannula and bloods?

I know everyone is busy so I want to say this is not to say otherwise. I just struggle with what to do as I feel like it can be obstructive to patient care.

I work in this hospital where the surgical assessment unit is where I see referrals from GPs when I am on call. When I am busy on call receiving call from A&E, GP etc. and when I accept unwell patients from GPs. I kindly ask the nurses on the surgical assessment unit to put in cannulas and take some blood for patients whom both GP and I think are unwell/septic and likely need admissions. Some nurses are always helpful and help us out but there are certain sisters would say something similar to this in a very condescending and angry tone. I was told this yesterday in a very rude tone "You come and see patient and when you feel you need cannula or blood you can do it yourself. We are very busy." This is even when I explained this is someone who is sick and I am stuck in A&E. Then I came up and saw that they were all sitting around chatting away after doing obs.

There was one time in the past I asked why not and they said it is policy from the lead consultant that nurses here don't do blood or cannula. I then found out that there are only 2 specific difficult sisters who would take this stand. Whenever they are working, no bloods or cannulas even if they just sit there chatting. I never had time and effort to take it up further to find out what the lead consultant actually said. I just let it go.

However, this is increasing difficult and I feel sometimes obstructive to patient care. At points, I felt like a datix of safety needed to be submitted

Am I being unreasonable? I want some perspectives and if I am not, what should I do?