Getting out of service agreement of partner mortgage financing brokers

Hi,

We reserved an apartment in December 2024 through a reputed broker with a prepayment of 30000 CHF to the owner of the apartment. As part of the process, the real estate broker mentioned that it is mandatory for us to use their partner services for the mortgage offers as a lot of people are interested in the apartment.
We signed the service agreement which mentions that if we decide to take the financing from a third party instead of the partner service, then we have to pay 1500 CHF or demonstrate that we got a better offer from the other brokerage provider.

Now the catch is that it seems clear that we can receive better mortgage offers from a third party service as compared to the partner mortgage broker. However, the third party is also asking for a commitment before they put in all the effort in finding the right mortgage as they are concerned that we will eventually not take their offer due to the service agreement.

In addition, the communication with the third party is a lot smoother and transparent and informative as well.

How do we get out of the service agreement? Currently, we haven't received a formal offer from the Partner company yet, they only show us values in the video call.

Can they penalize us in any way? Either through the service agreement, or the original real estate deal?

We have signed a reservation contract and paid an initial reservation amount, but we haven't signed the purchase agreement yet.