tommy just swap the nte5, if it doesnt fix the problem get back on to plusnet.
I confessed to the openreach CEO I had swapped the nte5 (breaching my t&c's), I recieved no punishment as they knew their engineers messed up by not swapping it out.
Well i did as you suggested and it appears to of stopped the crossover effect when the phone is in use, the attainable rates will reduce as well as increase instead of what it did before i swapped it, a slow reduction over time
not to sure if there is any improvement regarding error rates as yet,