You purchased the monitor from Northern Ireland, so it would come under the UK consumer laws.Unless you purchased for business use under a special terms and conditions contract, but this is usually not the case in 99.75% of purchases. Your claim for a replacement or repair will be the original suppliers responsibility, so contact them. Most monitor manufacturers will deal direct, and usually this is the better way to go for quickness on monitor problems, so I would also contact them and see what they suggest.The details of the manufacturers service and support, should be on the warranty details that you should have received at time of purchase.The supplier should also have these details.
Most monitors come with a three year manufacturers warranty, and most will do a swap-out service.This usually means that they will exchange your monitor for another unit 'equivalent too,or better than' the monitor unit that you already have.The warranty will continue,as it left off,upto the original full warranty period. I would also mention that your location in the Republic would also have EU consumer law advantages, like the rest of the EU governing states.