Perhaps you could post a picture of what it looks like now.....the old cable does look like a non standard kit, possibly done by a previous occupant ( if not done by yourself ) perhaps someone relocated the phone socket themselves , and didn't do a particular good job , the fault you had being a direct result of that dodgy involvement in 'Openreach's' network.
It always seems unfair , if the fault was before the master socket , and you were not responsible for the dodgy work, but arguably it wasn't OR 'fault' either, if whoever had done this 'work' had left it alone, or got it done by OR properly , then chances are it wouldn't have developed a fault, or if it had , it would have been covered by 'fair wear and tear'.....if you knew this was where the problem was , it would have been better to ask advice on if the repair would be chargeable , before asking your provider to send OR out
