Welcome David. From memory yours is a moulded unit and I very much doubt you will get a new one. A long shot might be a caravan salvage company breaking a van, but I think your best chances would be a repair. I'm guessing it is cracked. Have you any experience with grp as you could bond this on the underside to form a repair. If not do you have a boat repairers nearby as they deal with such matters on a daily basis.
Colin