I know exactly what you went through, cos I used to be one of the salesmen who pushed and pushed. Not through choice I hasten to add. It's a fact, in the store where I worked, that the Medions were (and still remain) excellent value for money, in fact, they are sold almost at cost, which is why they push so hard on them.
Please remember that it isn't the salesmans fault. I know this sounds like a passing of the buck, but the sales manager was, most likely, making him go back over and over. I, personally, got so sick of it, the pressure from the manager to keep the PC Performance percentage (its how they measure levels of extended warranty sales) up above 8% (8% of total store sales should be on PC Performance or else!!!) that I ended up transferring into the PC Clinic tech centre.
I would suggest that, you go back to the store, ask to speak to a manager, explain that you want to spend your £1000, but do not want the warranty, you do not want to discuss it in any way whatsoever, and does he want your £1000 or not - emphasize that you will not take the warranty under any circumstances, and that if it is mentioned, you will walk, permanently, this time. Be stubborn and awkward, if they ask why you dont want it (a usual tactic, so they can try to talk you out of your reasons) simply repeat, I don't want it, and I don't want to discuss it....
Good luck, its worth going back cos the medions really do (or did a year ago) offer the best value for money of any PC in the store.