I have an Epson 300R, and I had similar problems ( and similar responses from Epson).
I thought it may be my "inferior inkjet carts", as Epson suggested.
However, the R300 uses six separate carts, and although they all showed varying degrees of low ink, I eventually solved the problem ( by luck) by just replacing the BLACK cartridge only. For some unknown reason, this seemed to be the key for the other carts to behave properly!
I have never had any further problems!
Let me know how you get on, please.