It has been four days now since I changed the nameservers at my registrar from my old hosting company to this one (ns1.servermatrix.com and ns2.servermatrix.com) but after four days the domain is still pointing to the old server. Is this normal?

No, the changes should have propagated by now, what is the domain name?

movietrack.net

These are your old name servers right? Can you double check your changes with the registrar?

Yep, those are the old ones but I had switched them at my registrar 4 days ago to the ones here. When I log in to my account at my registrar it list these one here not the old ones. I don't understand.

Also at the same time, check if you submitted that domain name in Domain Admin in Orbit. If you have not done so, the entry will not be found in SM's nameservers which could cause a problem too.

I have done that as well...but now that I looked at the zone details in orbit, the nameservers are ns1.theplanet.com and ns2.theplanet.com...could this be the problem? I specifically told them in the ticket that I pointed them to ns1.servermatrix.com and ns2.servermatrix.com.

I just checked and ns1.servermatrix.com gives authoritative answers for your domain, so thats not a problem. The root servers are just giving the wrong NS records for your domain. You might want to contact your registrar.