Intermittent Voice Quality Issue

[#1]

We have reported this issue to Plusnet on a couple of occasions but because it's intermittent we cannot be certain which calls will affected. Each occasion Plusnet ran line tests but they pass. Because in that instance there is no speech issue
From our end the voice quality is fine, it is the other party, the calling or called party who hears severely distorted speech, it's so bad they have to hang up and try again, the caller can tell there is going to be a problem before we answer because the ringing tone they hear is distorted
We've been told to try different phones but to me this seems an unreasonable request because it is not the phones in the house which generate the ring tone hear by a caller.
Who can we get to investigate this long running intermittent problem? Wouldn't it be nice if the priority was to fix the problem as opposed to closing the support ticket
Our concern is that as the problem is intermittent if the problem is not observed in a short time, PN will impose a charge and the problem won't be fixed
Thanks D

[#2]

You won't be charged if the fault is not present when an engineer attends as long it's not damage to BT equipment,  your internal wiring or equipment.
You may however need more than one engineer as it will need to be occuring when the engineer attends for them to locate the issue in most cases.
Hope that puts your mind at ease.

[#3]

Thanks for the reply, Next question is how to get plusnet to escalate this when the line test passes  ?

[#4]

You would need to accept the potential charge and book a engineer slot that suits you.
Probably best to check the weather forecast as well I suppose!
If your calling,  just advise you have done the checks (test socket and different handset without a filter plugged in) and you would like to book an engineer.
It will save you being asked the same questions and make things quicker.