Help for Removing POOLING DOCUMENTS error

While I was paying fee of KVS on Union Bank Portal, the first try was failed, reason I don't know and from second onwards attempt every time I see an error massage as "Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached." Please help me to come out from this problem. As I have to pay the fees.