// Create a Map to store all the data of a Customer
Map<String, Object> customerMap = new Map<String, Object>();
customerMap.put('DisplayName','Weiskopf Consulting');
customerMap.put('Id','1201');
customerMap.put('SyncToken','0');
// Initializing the RequestJSON Data to be passed.
Map<String, Object> requestJSONMap = new Map<String, Object>();
requestJSONMap.put('customers', new List<Object>{customerMap});
String reqJSON = JSON.serialize(requestJSONMap);
Map<String, Object> reqObj = new Map<String, Object>();
reqObj.put('version', '1.0');
reqObj.put('action', 'updateCustomer');
reqObj.put('requestJSON', reqJSON);
//Required, if QuickBooks Multi-Org is enabled in Breadwinner.
reqObj.put('qbOrgId', '!aa00TM');
// Placing a request to Breadwinner Global API
Map<String, Object> respMap = breadwinner_qbo.BreadwinnerQBAPI.call(reqObj);
System.debug(respMap);