Board Thread:Support Requests - Community Management/@comment-6723989-20180203185826/@comment-9605025-20180203191119

Have you tried blocking the user's IP? If so, I would use Special:Contact/user-conflict and explain the situation. Ask them to do an IP check to reasonably verify that these accounts are, in fact, the same person. If they are indeed the same person and they are using different IPs to circumvent the block, you can place, or ask staff to place, a block on that user's entire IP range.