Expecting 'compensation' is unreasonable, yes. Waiver of line rental (as you had) or diverting incoming calls to your mobile are the reasonable solutions. In either case outgoing calls from your mobile remain your responsibility.
I'm a bit surprised that the BT engineer had to visit your home but it depends when you placed the order. PN switched to wires only install a month or two ago so most installs shouldn't require an engineer unless a new line is being ordered or you are switching to an FTTP solution.
As for top rated..lol. You've been reading too many adverts. Plusnet has been going downhill (at least in customer service terms) for most of this year. They are now officially (according to Ofcom) the second most complained about Communications Provider in the UK. If you have a stable connection they are great value for money which is why I have stayed with them. But if you ever need to call on their Customer Service you soon realise why they are cheap.
All I can conclude with really is that if you now have the connection you want you should be good to go. As long as it stays that way you'll enjoy your time with PN.