Ongoing connection problems

[#1]

I've been with plusnet for over 2 years now, usually no problems at all.
Last Saturday I woke up and my connection was terrible out of nowhere, constant connection loss (sometimes taking upto 10 mins to re-establish), sometimes crackly phone line, 1/3 download speed and just random awful unreliable connection.
I phoned up Saturday and I was told it could take 72 hours and to put my old plusnet router back in place (which I did), I've been waiting for them to contact me.  Well it's Tuesday now and I haven't had any contact (i know 72 hours won't end until 7 tonight but still, no updates?)
I would phone but it takes upto an hour to get a response at all, is there any way to know what will happen next?  will BT send someone to the exchange to fix this issue today, will they come to my house?  Is the 72 hours a testing phase and I'll have to wait a further 72 hours for BT to send someone?
I had this exact same issue about 18 months ago and the BT engineer took over an hour to find the cause that time, he replaced a part in the exchange to fix it on that occasion. 

[#2]

Hi there,
The 72 hours is for us to pick up on the ticket, test the line and report the fault with our suppliers.
I'd offer to pick this up or flag it to our faults team but we're not outside of that time frame yet.
If you don't have a response by this evening do reply back here and we'll get that done for you.

[#3]

Hi again, thanks for the reply.
I had a response to my ticket after I posted and was told the wholesaler (I'm guessing BT) would look into it within 72 hours.  I was told last Friday (the last day of that time period) was the day they would do so.
I've had no updates on my ticket or contact since then so I don't know if they did or didn't look at it but I'm still having problems with my line (although not as bad as it was it's still not working properly with intermittent heavy crackle on the line, low fibre speed and regular line drops). 
Just did a speedtest check and it gave me: 208 ms ping, 2.86 mbps download, .66 upload.  This on an unlimited fibre line that normally gives 25+ mbps.