how to prevent a mild DOSS attack?

hi guys, this morning I got complains from website owner and tons of visitors - nobody was able to access the website. it will just timeout. I contacted hosting company for more info but they said the virtual privet server, where the website is, has a lot of traffic and 512MB of RAM is not enough and I have to make an upgrade to at least 1GB etc. it does a make a sense. though, at 4pm I, nor 10 other people I asked for help, was able to access to the website. it was a little bit fishy about BIG traffic whole day long (the website is far from it) and, since I don't have a problem accessing WHM/cPanel of the server, I downloaded apache access file (stupid, I supposed to do it in the morning) and found 20-30 IP addresses, repeatedly were trying to access one (only one) page (something like article.php). and they were requesting the same page so frequently - nobody else was able to access to the website. it looked to me like a little DOSS attack - where attacker wanted just to make the website busy, not to crush the server. I contacted hosting company again. they said there is nothing they can do about this- even I'm paying them to manage my virtual server (I can manage this way by my self too). of course they can if I pay extra :-( now, my question is: is there anything I can do to stop these attacks using php? something? anything? thanks L