Hi granable, sorry to hear about your problems. I bought my brother an EM4800 for his wedding around 7 years ago and its still going strong. Only ever needed new seals, as one would expect. Has been used almost every day during that time (apart from when they were overseas for a year).
What is your cleaning regime like? Are you cleaning out the filter basket? Perhaps there is a build up of crud which is making the pump work harder, hence the noise and bad tasting coffee.
If youre confident youre doing all the right things in terms of cleaning, then do no hesitate to return the machine.