I have had issues with them finding a vein before, but they always kept trying and found one eventually so I don't recognise others comments about having one go then having to cancel.
The severe overrunning, having to book months in advance and inconvenient times to try and fit in an appt however! I used to have 2 centres within 2 miles of my house, luckily I wfh and was allowed time during the day to go, but they were often running at least an hour over so I couldn't stay.
We have now moved and the nearest centre is 30 mins each way. I booked in March for an appt at the end of July! I will see how this goes, but if it is too much of a pain then I won't be able to go much more.
Plus the constant phone calls if you havent donated for a little while, each time they rang I told them I had moved, and had my head on sorting out my house and etc and would arrange a date when I was sorted, but they would ring every couple of days, which is why I booked the July appt just to get them to stop!