Internet Speed Question

First let me say that I don't know much about this so excuse my ignorance.  I have been with Comcast now for many ears.  I was with them when they were Adelphia.  With Adelphia, I had the slowest of the three packages that they offered and it always worked fine.  When Comcast bought them out, I kept paying the same amount ($25.95 a month) but Comcast only offers 2 speeds now.  Not sure what I have but things have been slowing down.  It seems like my service is quite a bit slower and seems to be cutting in and out.  It will go out and I will go and unplug the router and modem and plug them back in and that will help.  I called service the other day and they kept telling me it was because I had the slowest package and I needed to upgrade.  I tried explaining to them I haven't had any problems until about a week ago.  I just checked my speed and I have nothing to compare it to but it said my download speed was 5836 kb/s and my upload speed is 278 kb/s.  I don't know what it was before so I don't know if this is slower or not.  To upgrade to the next package would double my cost and they just raised my cable bill and dvr bill.  I refuse to pay another $25 when I think they are the ones messing with my speeds to force me to upgrade.  Am I being silly here?  My other option is Embarq dsl which I know nothing about except a friend has it and seems happy with it.  What should I do?