do not change the breaker yourself as you may beam yourself up, in case you had not noticed in your answer 15 amp breakers are not the correct rating for a ring main but 32 amp and i feel this maybe an indication that your electrical experience is not vast
when you say you checked with a circuit pen do you mean you waved it around close to the socket or touched the faceplate of the socket?
this does not prove the quality of the terminations within the socket, if this is what you did
i would consider proffessional help to assist you with this one