This is sme forum. You probably have better luck asking at
http://www.dslreports.com/also, you are probably going to have to find someone who knows how the telecom industry works in CA as it's different in all countries.
Most DSL services are 'best effort' services, not guaranteed services. In other words, you get what you get. If you have poor dsl performance, it doesn't suprise me. It varies upon geographical location.
Most likely, your dsl upstream can't handle the load, slows, then drops. Your only option is to increase the service to a guaranteed service.
I can't imagine the 450 is a DSL service. Most likely it's some type of factional/full T1/E1 service that they manage. Because of it's increased upstream, your performace should certainly improve with this type of connection.
I've run into cases where T1's are misconfigured on the ISP side of the network. In which case, you can't do much about it other than change providers.