starters, not starter's
PSEs, not PSE's
standards, not standard's
gets, not get's
brakes, not breaks
weeks, not week's
That said, VM do a moderate job of running a very high speed consumer network. It's not perfect (of course). I wouldn't regard them as "very good" either. Right now we have customers getting notifications that VM will be cutting their services during core hours to perform maintenance. Well that's no use for businesses (and yes, they're on business contracts). They are notoriously bad for the quality of SIP/RTP connections, and they seem to have a fetish for mangling SMTP sessions heading out of their network (even if you start playing musical port numbers). But you know what? They're cheap for the bandwidth you get.
But yes, they are ultimately responsible for the conduct of their contractors. Just like McDonalds is ultimately responsible for the quality of their burgers. Just like my boss is ultimately responsible if I bin an email server by mistake. The buck stops at the top. That's how it works. That's how it needs to work.
If VM have appointed a contractor that does a piss poor job, they have to get that contractor in line. If the contractor can't do a good job for the price then that's the contractor's problem, but it's ultimately VM's responsibility.