Poor Linespeed/Strength and Service

We have recently upgraded to a faster linespeed package with Herotel and have had DAILY issues with our linespeed. It is really poor and not even 25% of what we are paying for. I put in daily emails to their support line and all I get in return is automated emails saying that a ticket was created. When we dial their number we are asked what router we use (they have installed it) and then miraculously our linespeed improves. This happens DAILY. This was not the case before and we have always had great service from Igen / Herotel but something has changed the last two weeks and they are not able/willing to resolve the issue. Really fed-up with this now!