As a longtime BulkRegister / eNom customer, I've have never seen this.
Typically, DNS propagation for eNom parked domains, such as expired ones, occur same day; often within one hour.
Have you checked the master whois for the TLD(s) of the domains in question to confirm your DNS updates were made? If not, try that. For .COM / .NET, check at VeriSign WHOIS - Domain Name Lookup from VeriSign, Inc. For .ORG, check at .:: Public Interest Registry ::... for other TLDs, query google for the registry URL to check.
While I've never seen the exact issue that you describe, I agree that BulkRegister has been absolutely terrible since their acquisition by Enom a few years ago. I've had locks appear mysteriously on random domains (nothing to do with renewals or registrant changes), and they are the slowest I've dealt with on registrar transfers (out). On at least one occasion, the auth code that I received from them was outdated (I initiated the transfer the same day), causing a transfer failure. And, of course, all of this at much higher than market pricing.
I have seen registrars 'default' domains to their own nameservers, in order to take advantage of the advertising dollars, but I can't recall having any registrar actually change the nameserver settings to their own, except in cases of domain expiration...
Hi.the same thing did happen on me once but I had no idea what to do with it except let it be that way.I never have my domains with it any more since then...
Are you sure you changed the nameservers to your own? Is it possible you forgot, also is it possible that you made changes to the domains that resulted in the nameservers being changed back to theirs?.
Many registrars put advertising on newly created domain names but to fix this you simply change the nameservers to your own (or place a html file on the hosting if they host the site).
Also the server you have is it provided by them? If they have provided the server they may have changed the skeleton files in apache so instead of having the standard apache index page you have 1 with their advertising...
Are you sure your name servers are setup right or that you added the domains correctly to your server? I had this same issue one time and here I came to realize that when I added the domain to my hosting I made a typo!..