Still being billed for a service cancelled in 2017!

[#1]

I realise I am totally stupid for not checking my bills regularly, but I have just discovered I am being billed for a service I don't have!
I cancelled Voicemail (Extra) on 25/8/2017 and have an email confirming this, but on checking all the bills I can currently see on my account, I am still being charged for it.

Tried calling but message basically says don't bother unless it's an emergency and I am a vulnerable person, don't use Twitter and don't appear to be able to email you, so how do I get this sorted?

[#2]

Welcome to the forum @AS_ker1   😊

As things stand, you've done the best you can by posting on the forum, which is frequented by staff as well as customers.

Might be a while as obviously there are some more pressing problems to sort.

Meanwhile, what does this page say?

[#3]

Thank you  @198kHz 

That page definitely says I have £3 of additional features, but interestingly it now also says
Change already in progress

You are not currently allowed to make a change. There is already a change in progress. Please try again later

Didn't notice this message last time I looked at this page - could have missed the message before, but hopefully it is new and means someone is doing something!  Hope so!

I only actually looked at my account page and discovered this because I was looking to renew and upgrade my service ...not so sure whether I want to bother now!

[#4]

Still no reply from Plusnet.  Still being billed for a service I haven't had for 3 years.

I know things are really difficult at the moment, but if I can't call and I don't use Twitter, how do I get this sorted?