Hi Les,
from memory I think the parking assist light flashes instead of constant and a I received a permanent beep when putting it into reverse.
I ordered a replacement speaker from eBay for a few quid (Parking Sensor Warning Buzzer Speaker Buzzer 8E0919279)
Then it really is as simple as unplug the old one and plug in the new one. I
The speaker wasn’t fixed to anything on mine, it’s just sitting loose behind the driver side rear seatbelt cover.
I’m sure there is a few YouTube tutorials on how to remove the plastic coverings but I don’t remember it being too challenging.
Good luck 🤞