diff --git a/lib/active_merchant/billing/gateways/netbanx.rb b/lib/active_merchant/billing/gateways/netbanx.rb
index <HASH>..<HASH> 100644
--- a/lib/active_merchant/billing/gateways/netbanx.rb
+++ b/lib/active_merchant/billing/gateways/netbanx.rb
@@ -55,6 +55,10 @@ module ActiveMerchant #:nodoc:
         post = {}
         add_invoice(post, money, options)
 
+        # Setting merchantRefNumber to a unique id for each refund
+        # This is to support multiple partial refunds for the same order
+        post[:merchantRefNum] = SecureRandom.uuid
+
         commit(:post, "settlements/#{authorization}/refunds", post)
       end
Merrco partial refunds fix (#<I>)

As per the Pay safe API documentation and our discussion with their representative we know that the merchantRefNum has to be unique each time we communicate with the API. Also we specifically asked that if the merchantRefNum has to be the order id, to which the answer was no. It can be any random string, as long as it is unique each time.