Depending on how long you're going to use it for, renting may not be the cheapest option. There are several double pumps out there that are very good and they are much smaller and more portable than the massive rental pumps that come in a small suitcase. You will also have to buy all your own parts to go with the rental pump. Also, check with your health insurance, they may pay for some/all of the cost of either a rental or purchasing a pump.
Not sure where you can rent one though sorry, maybe just try around some other pharmacies or have a look at
this thread
Link from Medela website shows where you can rent in Switzerland.
I bought a Medela Freestyle (subsidised by my insurance) and highly recommend it after using it for the better part of a year after going back to work.