I wonder if the WTS is attempting to claim that Turnover does not include donations?
That's probably the case, but if you submit a response claiming donations are turnover, the worst they can happen is say it isn't. If there is no cost to you than it may be worth your time! I found this: Small Business in Australia, 2001--Australian Bureau of Statistics
TURNOVER Sales of goods and services, commission income, repair and service income, rent, leasing, and hiring income (excluding unallocated rent, leasing and hiring income), government bounties and subsidies, and all other operating income except interest, royalties and dividends. Also included is the value of capital work done by the management unit for itself and the value of equipment withdrawn from stock for own use or for rental or lease outside the management unit.
You could try to say that donations are operating income and so is the value of the highlighted items, and see what happens. (In addition to responding to all the other points listed above.)