need a tank for a solar hot water system

I have a 5 year old solar hot water system consisting of a 250 litre storage tank and two glass panel collectors. The tank has a fairly large hole in one end and seems to be unrepairable. I've had one company, Monosun, have a look and they want to replace the entire installation which seems a shame as the collectors work fine. Anyone know of a company that might have the storage tank? The name on the outside of my tank is SolarComfort. Thanks