After the first failed attempt, every time you have made an appointment, I have told the person I was speaking to that the property had a fused neutral, and that E.ON needed to make arrangements with SSE to change that. And every time, E.ON has failed in their duty of care to do that.
In each case I have had to rearrange my working schedule to accommodate the installation appointment. I now request some sort of consideration of the not insignificant amount of time and effort I have expended on emails, phone calls, and rearranged schedules due to your failure in your duty of care in this matter.