Hi,
If it was a breakdown involving a lost/broken key in all likelihood you'd be recovered to somewhere that could sort you out. Breakdown doesn't cover the cost of parts, so not the cost of the key itself or any programming I'm afraid.
The provider is SilverKnight Rescue and they use a nationwide network of independent recovery operators. We rarely receive any complaints and their average callout response time is just 38 minutes.
Hope that helps.
best,
Nick