"Blood test problems"

I had a recent request for a blood test from my Dr, upon arriving at the blood test clinic the nurses were unable to obtain any blood from me. I would like to point out that the nurses were very nice about it.

I appreciate I am not an easy person to take blood from. I was told that my Dr needed to make an appointment for me at the MAU. My Dr phoned MAU but they refused to carry out the request. So now I have un-investigated health issues because no blood can be taken from me. I am sure with a bit of time and patience it could be. I must have some veins in my body or how does the blood circulate. I just don't have surface veins visible to the eye, bu I am sure with some preparation maybe a heat pad or if I did some exercise before it could be resolved. I am now concerned I might have diabetes and liver functions problems that will only get worse without some proper investigation