In the shop guidelines, you will find the phone number that you need to call - simply call that number, and when prompted enter the shop ID number. You will be automatically forwarded to the location you're shopping, the call will be automatically recorded and uploaded in your shop report once you're done.
Thank you, and good luck!
I would also suggest that you record your own either via a separate recorder, or via your smartphone set on speaker phone. The reason for that is that when you are writing your report, you may at times not have full access to the recording, plus on your own you can forward and back space to get to the relevant parts of the recording.