@endocrinegremlin the fact that you are in Scotland has nothing to do with your problem. I think your so-called DSN is the problem, as she insists your Mio should last 3 days. I attend a Glasgow hospital and have been using the pump for 9 years. From the early months, I have had to change my set every 2 days, as my blood sugars would be in double figures on day 3.
Your problem is different from mine, as your skin seems to react to the set. It's a good idea to try different sets, especially the Sure T that
@Juicyj mentioned. However, you might have a problem when asking Medtronic for sample sets. When I asked to try the 6mm Mio, as I'd been having pain in some sites with the 9mm, I was told they couldn't do this without permission from my DSN. The fact she was on holiday didn't help matters.
Ask your "DSN" to try different sets and if she still blames you, ask to deal to her superior. If you don't get any satisfaction, ask for a copy of the complaints procedure and take it further.