Hi can anyone help. The white plastic shower tray and other plastic parts in the washroom area of our Hymer Exsis 572 has been badly discoloured by uv rays from the sun through the skylight. Is there any way of removing this colouration, re-coating the plastic, or do we just have to live with it? Other motorhoming folks must have or had or have this problem. . . . . . . . . Or is it only me?