Hi Nic,
I was at my wit's end with this keyboard situation, now I've given up. I eventually solved the screen jumping problem with a complete reset, and using it as a tablet for reading kindle books and PDFs - a £1200 eBook reader!!! FFS...
Putting it down to experience I'll be steering clear of Microsoft devices - it's not the problems so much, it's the lack of good customer service that really counts. We know that they are just typing crappy solutions over-and-over again that we can't use to any effect. My surface pro 4 keyboard packed up 6 months out of warranty. I'm just not willing to pay more money to Microsoft for a problem I didn't create. I've told everyone I know about my Surface Pro problems and lack of impetus to adequately fix the issue - word of mouth counts for a lot.