Re: 10% in Error? BullShit!!! Every one of my PC's has attemped to install Win 10 Crapware!!!
Did it install without your consent? Even better, have you at some point unticked the "download and install this crud on my computer if I dare come near any usable network" box?
In that case you may have a valid complaint under the UK Computer Misuse Act 1990 as it's amounts to unauthorised access to your machine - possibly a criminal offence colloquially known as "hacking". I'm not quite sure who handles this, but as it's a consumer issue I'd say it would be best if you get the government to help you organise the complaint. I don't keep up with who Trading Standards gets to handle the public anymore, but they appear to be the first port of call. The "criminal" aspect means that the state organises any possible prosecution, but I suspect that requires more than one complaint, so I would recommend anyone who had an unauthorised install to complain.
Speaking of Trading Standards, there is a secondary aspect here - as this upgrade is forced upon you, it is possible to argue that the new T&Cs were agreed to under duress and thus invalid.
Key is that you decide on the remedy you want. Restoring the original OS seems to be the sensible option, and, of course, abandoning any attempt to do this again. It isn't right that a third party has to come up with a remedy (keep mentioning this, because MS is apparently trying to get it flagged as spam) for what is IMHO simply abusing the user's last fragment of trust to force them into installing something they absolutely do not want (a fact proven by the fact that Win 10 upgrades were not exactly widespread).
Or switch to an OS that leaves you a choice. That's any other OS..