Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Hi there, sorry to hear you're having trouble,
I would suspect that your answering machine isn't actually the problem here, and is probably working just fine.
I'd like you to test something for me please: could you please unplug both the power cord and phone line going to your answering machine, and then call your home number from another phone (like your cell phone) and let me know if you still hear that "default message" you mentioned earlier.
If you do hear that same greeting in this situation, then what is happening is that you are reaching a voicemail service provided by the phone company. It is answering before your home answering machine has a chance to pick up the line, which is why you hear a different greeting, and you will also get no messages when checking your home answering machine.
Just as they added call waiting, they likely upgraded their equipment and switched on voicemail service as well. That is something that BT will need to disable, so that you may resume use of the panasonic answer system
OR as an alternative, you could get rid of (or just stop using) the answering machine and use the voicemail function instead. You can record your own greeting on the voicemail if you like, and voicemail actually has several advantages: it is always on, meaning it will work even if the power goes out, while the answering machine could stop taking or playing messages if it is ever damaged or unplugged. VM will also work even if you're on another call, with answering machine, the 2nd caller would just get a busy signal. For these reasons, I tend to recommend voicemail over using your own machine, simply because it tends to be more reliable and accessible. The choice is yours of course though.