I've had a lot of interactions with narcissists and I'd like to point out a flaw in the blocking system. When someone says to a narc that she/he isn't interested in talking to them, the narc takes it as a personal challenge to make that person talk to them again. If they block one number the narc will contact from a different number or even from a public booth. Blocking only works if the person concerned (in this case the OP) changes her number and moves to a different location.
A better solution is to become as uninteresting as possible in the eyes of the narc. Ghosting is a very effective way of doing it. Don't reply to 9 texts and in the 10th only say something non committal like 'meh' or 'OK'. Never ever pick up the phone. Ever. Just text back occasionally and try to gradually increase the gap between two texts. If the narc tells you about his achievement only reply with 'I see'. DO NOT OFFER ANY POSITIVE REINFORCEMENT. No congratulations. Never share any personal info with the narc. How are you? 'Good'. How is work? 'Usual'. Wanna know what my boss said today? No reply. Don't show the minimum curiosity in what he is saying. If you can be steadfast about it, usually it doesn't take long for the narc to lose interest.