I'm in a similar situation.
Recently upgraded from 200 to 500Mb, installed the new router and the best I've ever seen is 280Mb on the Speedtest app on my phone. Normally I get between 180-220Mb depending on the time of day
Does broadband still take time to bed in? It's been 10 days or so. Or am I thinking of the old days again
I'll probably give them a call but the T's & C's on the 500Mb are shocking, it implies no point in complaining unless it is below 258Mb