At 500m you should get better than 64/22.
How many phone outlets in your house?
And if they had incorrectly put you on a 25/5 plan then sync should have been exactly 28000/6400.
I don't think that's right. My modem has always synced at something like 135/52 since day 1 (I am only 150m or so from the node), but I initially started on a 25/5 plan before upgrading to a 100/40 (and my real-life speeds have reflected those plans).