Get Pivot DATA and if formula to return another value

Hi all, 

I am using pivot table data to build a data set and I am using the get pivot data..

so I have realised when I have two criteria for each profit centre. So the formula is adding together accessories and units to return the value. But there are certain profit centres only accessories/units and it wouldn't return the value as the formula is for adding these two together. How can I write formula to return value i.e. if there is no accessories - return the units value for the given profit centre and vice versa and also if there are values for accessories and units return added value of these together.

Thank you.

MSJ

Formulas and FunctionsExcel