More questions than answers here to be honest...
Your screenshots show good coverage but imply poor data speeds, which is different to your subject line that mentions "coverage atrocious" without any explanation - is that what you're reporting?
Irrespective, is this just in one specific location? "London" covers a huge variety of locations, both inner & outer. Is this a problem that's started recently? The standard answer is to check any specific locations on the website status tool, but if you can provide some further details on your issues, then more help can potentially be offered.
https://ee.co.uk/help/mobile-coverage-checker - "check coverage" checks for predicted coverage levels, "check status" searches for known issues.
