No specific suggestions except to decide up front that you need a new dispenser, have the repair place order it and show up at the first service call with the part in hand. I did that with a broken heater element in my KA DW and it worked out fine. The repair place told me that if I did it that way, I had to pay for the part whether or not it fixed the problem. I said fine, since it was obvious that the heater element was cracked in two.

You could also buy the part yourself and attempt to replace it yourself. I have no idea how easy that would be but you might be able to find youtube videos that show you how.
In my case, replacing the heating element was not straight forward - you had to take the bottom of the DW apart as well as the door, since the new heating element came with an updated control board that had to be replaced.

Good luck.

Depending on the cycle, the dispenser might not have opened even 15 minutes into the cycle. My Bosch can take up to 20 minutes before the detergent is released.

Here's a service manual for a dishwasher with a dispenser like the one your dishwasher has. Replacng the dispenser seems not too difficult. It also says on page 50 that you might just have to replace a spring.

http://elektrotanya.com/siemens_se25t250.pdf/download.html

Alex

I'm so sorry for the delay with my response. Thank you very much. I'll first try replacing it myself before calling for service. It does seem pretty easy to replace.

Again, my apologies for not responding sooner.