Here's a reworded version of the sentence:
Per your request, if the customer tells you that he would like to collect the cheque from our office, we will hold onto it until he comes to collect it.
If I were writing this statement for work, I'd emphasize clarity and make it obvious that I'm waiting for additional information. I might write something like this:
You asked us if we would be willing to hold onto the cheque in our office and give it directly to the client. We would be happy to do this if it is the client's preference. Let us know what the client wants to do and we'll act accordingly.