Indeed.
Mind you, your connection is extremely good, and interleave is increasing your sync rate (=speed/throughput) so it's a good thing, although you don't like the latency.
If your ISP is sufficiently clued up, they can disable interleave for you (I think, true for adsl1 on BTW 20CN anyway). If you succeed in getting them to do it, you will have a less reliable and slower connection.
There are things you can do to improve your connection quality and hence speed. Internal house wiring, good faceplate microfilter, outstanding short Tandy rj11-rj11 cable from modem to microfilter on wallsocket, mains purification, keeping mains cables away from other cables. The usual range of things that you will have seen too many times in my earlier posts.