There is another way. It is a thermometric titration with bicarbonate:
OH- + HCO3- <-> CO3-- + H2O
You use 1mol/L KHCO3 as titrant (it's more soluble than NaHCO3). It does need frequent standardization, but it has the advantage that it is not subject to interference. However, you do need a good automated thermometric titration system.