TWC customers -- Anyone ever downgrade service before?

Maybe a year and a half ago now I downgraded our TV service to the most basic tier. I meant to cancel cable altogether, but of course it was cheaper to keep that so I did. I lost the premiums, but nothing else at first. Eventually I did lose some random channels, but I kept the vast majority of channels I had before I downgraded.

Six months ago I wanted a couple of those missing channels back so I went back to the higher package. It didnt work immediately and a tech had to come out. There was a trap on the line that was supposed to be filtering out higher channels, but for some reason was only working selectively.

Yesterday, faced with some increased insurance premiums, I again tried to cancel cable and was again offered the basic package plus internet cheaper than just internet. I accepted and was told that the TV changes would be instant. Just like last time I have only lost my premium channels, ala HBO, and everything else is still there.

What gives? Is it the fact that I use a cable card instead of one of their boxes? I am thinking that someone will come out, put a trap on the line, and maybe this one will work right, but the last one didnt. What is everyone elses experience?