DRP residual ?

This might seem a bit pedantic but I find it interesting anyway. I have been participating in the ANZ DRP and if around the Div date the SP is high I sometimes withdraw and opt for the cash & re apply when the SP is low. I re applied before the last Div, thinking I had $21 residual brought forward from last time only to find that once I withdrew it went to charity and I had zero residual. Now I have no problem donating to charity, & I do. Apparently our Banks are very trustworthy but I'd still like the option to choose my own charity. Then I checked my WES account and found $40 gone as well as some others. Overall a couple of hundred $ disappeared. It's something I didn't think to check on until recently.
Not all companies choose to do this as my balance carried forward really did carry forward on some, but I am careful to read the Terms & Conditions from now on. Now I know in the whole scheme of things it's not a lot of money but imagine if somebody had Blackmores, COH, CBA and DMP, all between $70 and $120. That could add up to a bit residual cash gone every time you switch. Just something to think about.