Excellent news,
RR!
Just so you understand the terminology, abbreviations, etc --
Your line, which consists of two wires (hence you may read of references to a "pair"), leaves the telephone exchange in a very thick cable. That cable contains many pairs and is pressurised with compressed air. It is known as the E-side cable. The air pressurisation serves two purposes. By monitoring the pressure within the cable, it should be easy to notice any potential damage to the cable and also, if the damage is not too great, the positive pressure forcing air out of the fault will prevent any water, for example, getting in.
The E-side cable will run to a Primary Cross-connection Point (you will see references to a "PCP"). This, in the majority of cases, is the green coloured street cabinet. Within that cabinet there will be pressure gauges to monitor the air pressure in the E-side cable(s) and each individual pair from the E-side cable(s) are then connected to smaller distribution cables. They are D-side cables, hence reference to the "D-side". Now those D-side cables will then travel, often via foot-way joint-chambers ("boxes", manholes in the road/pavement, etc) where there are other joints made, cables tee-off to nearby premises, etc, until they reach their respective Distribution Point (a "DP"). A DP could be yet another underground chamber ("box") or at the top of a pole. At the latter there will be yet another joint in the pair were the multi-pair D-side cable is connected to an individual overhead Drop-Wire ("DW") or Drop-Cable.
At the premises. that Drop-Cable will either connect direct into the NTE5/A or there will be yet another junction in the pair where the Drop-Cable is connected to internal service cable. If the latter, the service cable will ultimately be connected to the NTE5/A.
All of the above is the property of, and is maintained by,
Openreach. As you can see there will be joint after joint after joint, etc, in a typical pair. If just one joint goes defective -- a complete fail or semiconducting or high resistance -- then there will be different degrees of problems with either the telephony or the broadband services (or both).
After typing all of the above, I think I deserve a quick cat-nap!
So, in summary, there was a defective joint somewhere in the D-side of your pair. An
Openreach engineer found the faulty joint and re-made it. Everyone is now happy, once again.