There will always be instances of one customer service rep who is clueless with any company.
However, as a few others have also noted in some other threads, my experiences with Vanguard as a whole have not been the most flattering. The biggest frustration was dealing with my grandmother's estate. I was not the primary executor, but was handling all of her investments and knew everything related to financial markets, etc. (dad was her official first executor, and either called V with me or I told him what to say/ask for when dealing with them).
They have a specific department for dealing with deceased V account holders (called something like "account transition team"). Despite having this specific department, and despite dealing with two different people, we received incorrect information on more than one occasion, and has to follow-up numerous times to find out where everything was at after several weeks of waiting.
I applaud V's ultra low cost - but if you anticipate needing ANY assistance with customer service reps, etc., spending just a few bucks more can be worth it in the long run, depending on what your portfolio looks like, how complex your portfolio/estate is, etc.
But lackluster service personnel isn't limited to V: having most of my accounts at TD Ameritrade hasn't really impressed me, either. I have an account rep assigned to me, based on my account balances. I had created a SIMPLE IRA earlier this year based on direction from my employer that they were going to go that route. However, they later decided to continue doing SEP IRAs, so my SIMPLE IRA account was never funded. My personal account rep saw that I had opened up my SIMPLE IRA and called me up and left me a voicemail saying that if I ever wanted to open up an account, I needed to contact him first to get some freebies.
So, when I needed to open up a solo 401k a few weeks ago for some moonlighting work for tax year 2015, I called him up after starting the online process and downloading the forms. They advertised on their website you can get 60 days of free trades with new accounts, when I started the process. When I talked to my account rep, he told me he would mark my account to get some free trades (but but but....you were advertising free trades for 60 days, so where is this special perk you said I needed to call you to get?).
Then he tells me I can drop off the application at their office! Not that big of a deal since I was going to be in the neighborhood, but otherwise could have been a 25 minute round trip drive. So I drop off the solo 401k forms and a $15,000 check to deposit.
2 1/2 weeks later (on April 14), I get 2 voicemails from him saying I "incorrectly filled out the forms". Doesn't say what I did wrong, just that it was incorrect, and that he needed to send back my check.
Apparently, he let it sit on his desk for a full 2 1/2 weeks before handing it off to someone to process! And the 'best' part - he says that he hopes I wasn't trying to beat the April 15 deadline to open the account (because apparently I would have been SOL if that were the case) because there's nothing he nor anyone else could apparently do to finish the application and deposit the check before April 15!) This took place on April 14 - but if I had corrected the forms that night - or even that afternoon - I could have run the forms over to their office that afternoon and still had 2 business days to process the forms.
Since a solo 401k must be open well before the end of the tax year, it wasn't applicable - but he obviously knew nothing about even the most basic of account info to know that. But if that had been the case, my $15,000 account deposit would not have been deposited, and that could have screwed up a last minute tax return refund/tax bill, as far as he knew!
Moral of the story: even if you have a 'dedicated account rep' due to high balances, sometimes they aren't worth their weight in dirt!