Worst service EVER.

[#1]

I've had 6 months of pretty much constant dropouts, half a dozen engineers visits, while having the pleasure of Plusnet taking  full payments out of my account. They've lift and shifted. Changed cables. All this after me proving it wasn't me, my cables, my computer. I even bought a new router- they wouldn't and won't send one despite it being under 12 months old but the same problems existed with the new modem/router.
It seems there has been no progress since the old days of 28,800 bps dial up modems.
Does anyone have any practical advice to get the service I pay for after 6 months of patience? Or is your advice to give up on what clearly seems to be a waste of my time and money. Or anything else?
I sent a complaint 7 days ago and despite their 7 day reply promise they haven't bothered even acknowledging receipt.

[#2]

I'm sorry to hear about the issues you've had.
I can see we've responded to your complaint this morning and the fault is with our Faults team at the moment.
As soon as they have a update they'll be in touch.