Cancellation Of Property Due To Covid

We are in the process of purchasing a resale property which is unregistered in Bangalore. As part of this, we paid a token amount of 3% along with 17% advance payment and signed an assignment agreement involving builder, seller, and us. It is 5 months and no progress happened. The seller resides in Switzerland and she could not travel for registration before the pandemic and because of the pandemic, we don't know when this can happen. Hence, we decided to cancel the deal and requested a refund of the amount made to the seller in this regard. The seller says we are free to cancel the deal but the amount will be forfeited because we are canceling due to pandemic and not a legal dispute. We have a token receipt duly signed by us and the seller. The assignment agreement is signed by us and the seller but not a builder. However, we have proof of all of them. Is there any way we can get the money refunded. Is there any law in Bangalore that buyer will lose all the money if they decide to cancel the sale.