Good news about them accepting the over voltage issue, did you ask about compensation for loss of income and all the messing about you have had to do when in fact it is down to them?
We got a very satisfactory settlement when our supplier didn't follow the path they were supposed to .
If they haven't offered any comp I'd get in touch straight away by recorded post to the head honcho at their complaints dept, so it is officially recorded that you are having a financial issue with them and are worried about the danger of over voltages above the legal norm affecting your electrical equipment & families safety .
When Stewart ( I've mentioned him previously ) had similar probs that's the route he took .
The local transformer was replaced four days afterwards and he hasn't had any problems since .
He wouldn't tell me what his compensation was , just gave me a big cheesy grin & a thumbs up ,so I assume it was eminently satisfactory .
In the early stages I don't think the electricity supply companies fully understood & made provisions for the effect of thousands of PV systems pushing power back into the system via local transformers and the little kick up voltages each one produces when pushing juice back to them .
I haven't taken any reading for the PV production for August as I've recently up dated to windows 10 and it's not accepting my web cam nor my IP cam drivers plus HP the makers of my computer don't have any either . I can't get up into the area where the meter is at present due to still heavily recuperating from my spinal surgery.