So considering I have an A500+ can I do anything to solve the flickering? I saw on eBay some flicker fixers but do not know if they are related!
No need for flickerfixers or anything! You can do what I did if you have an ECS amiga (500+): buy an Amiga 1438 monitor (or a Microvitec 1438, it's the same) and use HighGFX from aminet. You can have resolutions up to 1024x768 (with flickering) or 1024x384 WITHOUT flickering which is quite acceptable I believe! But remember, this can be done only with an A500+, not with an A500!