Since Plusnet added the extra Zap, I have had excellent latency. At peek periods, average 4Mb, quiet times 6.1Mb, considering my line attenuation is poor (-41db) I have absolutely no complaints. I try to keep within the 4Gb limit I am paying for.
If you read other ISP forums, then you may appreciate what you have.
At present, most ISP's are making a loss on the lower end offers.