Bernie,
Yes you can most definitely request a better offer from RAS. Well I did with SDCC, Play hard ball.
I gather from the above post you have your property in excess of a decade. While I do not have details on your financial situation I might assume that you are paying tax on your rental income at the higher rate. If this is the case 300euro might net you 150 euro.
A good tenant in my opinion is worth their weight in gold. Tread careful, dont be mean common sense. Best of luck. D