How to pass array attribute in config json using _configure Rest API

Passing this

jsonString = "{"bsId":" + transactionID_quote + ","documentId":12345567,"configData":{"pi_pays_Array":{"items":[{"value":"" + string(piWeeklyCount_c) + ""}]},"pi_controlOtherPays_Array":{"items":[{"value":"" + string(piOtherFrequencies_c) + ""}]},"pi_marketSegment":{"value":"" + piMarketSegment + ""}}}";

I'm getting error

{Status-Code=400, Error-Message={"o:errorDetails":[{"title":"pi_pays_Array is an array attribute. Please use array set payload to modify it's value."},{"title":"pi_controlOtherPays_Array is an array attribute. Please use array set payload to modify it's value."}],"type":"HTTP://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html","title":"Invalid payload."}

What do I need to change?